紧急求助两道GWD真题

GWD 30

Q17:

By the same techniques used for genetically enhancing plants, making them disease- or pest-resistant, researchers have been able to increase the amount of protein in potatoes, sweet potatoes, and tobacco.

1. By the same techniques used for genetically enhancing plants, making them
2. With the same techniques to genetically enhance plants, so that they are
3. Employing the same techniques used to genetically enhance plants so that they are
4. Employing the same techniques to genetically enhance plants, which makes them
5. Employing the same techniques for genetically enhancing plants that make them

为什么答案是C不是D? C的那个USED TO怎么解释阿

Q20:

Researchers have announced that the magnetic fields emitted by one manufacturer’s security surveillance system, of which type there are 200,000 worldwide, can interfere with pacemakers and that this interaction can bring on missed or irregular heartbeats, nausea, breathlessness, dizziness, and even fainting.

1. of which type there are 200,000 worldwide, can interfere with pacemakers and that
2. of which, worldwide, there are 200,000 of that type, and which can interfere with pacemakers, and
3. of which type there are 200,000 worldwide, they can interfere with pacemakers and
4. 200,000 of which type exist worldwide, interfering with pacemakers, and
5. 200,000 of that type existing worldwide and can interfere with pacemakers, and

为何是D不是A.....

Q29:

Researchers agreed that the study of new treatments for heart attack patients was extremely important but more research was needed to determine that balloon angioplasty preceded with ultrasound was or was not any better for heart attack patients than the balloon procedure by itself.

1. more research was needed to determine that balloon angioplasty preceded with ultrasound was or was not any better for heart attack patients than

2. more research was needed for determining whether or not balloon angioplasty preceded by ultrasound is any better for heart attack patients than is

3. that more research was needed to determine whether balloon angioplasty preceded by ultrasound is any better for heart attack patients than

4. that more research was needed to determine that balloon angioplasty preceded with ultrasound was any better for heart attack patients than

5. that more research was needed for determining that balloon angioplasty preceded by ultrasound is or is not any better for heart attack patients than is

这个答案怎么可能是B啊，NEED 后面跟TO  吧。。。怎么会是FOR 呢

GWD 30-Q17:

By the same techniques used for genetically enhancing plants, making them
disease- or pest-resistant, researchers have been able to increase the
amount of protein in potatoes, sweet potatoes, and tobacco.

 "making them
disease- or pest-resistant" is used to indicate the result of "By the same techniques used for genetically enhancing plants".

Both D and E distort this meaning.

C的 USED TO = Employing the same techniques (that were) used to genetically enhance plants;

For D,  both "which" and  "them" refer to "plant". So it wrong again.

Q20:

可以去看看讨论贴啊!也许有你要的答案！