请各位nn帮帮忙，偶逻辑真是不咋滴，就考了，无奈哦 ~~~~

GWD3-Q40:

Two centuries ago, Tufe Peninsula became separated form the mainland, isolating on the newly formed Tufe Island a population of Turfil sunflowers.  This population’s descendants grow to be, on average, 40 centimeters shorter than Turfil sunflowers found on the mainland.  Tufe Island is significantly drier than Tufe Peninsula was.  So the current average height of Tufe’s Turfil sunflowers is undoubtedly at least partially attributable to changes in Tufe’s environmental conditions.

Which of the following is an assumption on which the argument depends?

A.      There are no types of vegetation on Tufe Island that are known to benefit from dry conditions.

B.      There were about as many Turfil sunflowers on Tufe Peninsula two centuries ago as there are on Tufe Island today.

C.      The mainland’s environment has not changed in ways that have resulted in Turfil sunflowers on the mainland growing to be 40 centimeters taller than they did two centuries ago.

D.      The soil on Tufe Island, unlike that on the mainland, lacks important nutrients that help Turfil sunflowers survive and grow tall in a dry environment.

       E.  The 40-centimeter height difference between the Turfil sunflowers on Tufe Island and those on the mainland is the only difference between the two populations.

Which of the following most logically completes the passage?

Appendicitis (inflammation of the appendix) is potentially fatal; consequently, patients with symptoms strongly suggesting appendicitis almost always have their appendix removed.  The appropriate surgery is low-risk but performed unnecessarily in about 20 percent of all cases.  A newly developed internal scan for appendicitis is highly accurate, producing two misdiagnoses for every 98 correct diagnoses.  Clearly, using this test, doctors can largely avoid unnecessary removals of the appendix without, however, performing any fewer necessary ones than before, since ______.

A.      the patients who are correctly diagnosed with this test as not having appendicitis invariably have medical conditions that are much less serious than appendicitis

B.      the misdiagnoses produced by this test are always instances of attributing appendicitis to someone who does not, in fact, have it

C.      all of the patients who are diagnosed with this test as having appendicitis do, in fact, have appendicitis

D.      every patient who is diagnosed with this test as having appendicitis has more than one of the symptoms generally associated with appendicitis

      E.  the only patients who are misdiagnosed using this test are patients who lack one or more of the symptoms that are generally associated with appendicitis

Which of the following is an assumption on which the argument relies?

A.      Infectious diseases other than typhus to which the ancient Nubians were exposed are unaffected by tetracycline.

B.      Tetracycline is not rendered ineffective as an antibiotic by exposure to the processes involved in making bread and beer.

C.      Typhus cannot be transmitted by ingesting bread or beer contaminated with the infectious agents of this disease.

D.      Bread and beer were the only items in the diet of the ancient Nubians which could have contained tetracycline.

E.       Typhus is generally fatal.

30. GWD21-Q30:

In the past, most children who went sledding in the winter snow in Verland used wooden sleds with runners and steering bars.  Ten years ago, smooth plastic sleds became popular; they go faster than wooden sleds but are harder to steer and slow.  The concern that plastic sleds are more dangerous is clearly borne out by the fact that the number of children injured while sledding was much higher last winter than it was ten years ago.

Which of the following, if true in Verland, most seriously undermines the force of the evidence cited?

A.      A few children still use traditional wooden sleds.

B.      Very few children wear any kind of protective gear, such as helmets, while sledding.

C.      Plastic sleds can be used in a much wider variety of snow conditions than wooden sleds can.

D.      Most sledding injuries occur when a sled collides with a tree, a rock, or, another sled.

E.       Because the traditional wooden sled can carry more than one rider, an accident involving a wooden sled can result in several children being injured.

想请问D哪里错了？

30. GWD21-Q30:

In the past, most children who went sledding in the winter snow in Verland used wooden sleds with runners and steering bars.  Ten years ago, smooth plastic sleds became popular; they go faster than wooden sleds but are harder to steer and slow.  The concern that plastic sleds are more dangerous is clearly borne out by the fact that the number of children injured while sledding was much higher last winter than it was ten years ago.

Which of the following, if true in Verland, most seriously undermines the force of the evidence cited?

A.      A few children still use traditional wooden sleds.

B.      Very few children wear any kind of protective gear, such as helmets, while sledding.

C.      Plastic sleds can be used in a much wider variety of snow conditions than wooden sleds can.

D.      Most sledding injuries occur when a sled collides with a tree, a rock, or, another sled.

E.       Because the traditional wooden sled can carry more than one rider, an accident involving a wooden sled can result in several children being injured.

想请问D哪里错了？

我觉得D没有提到plastic和wooden的区别。。。。。