有语法问题[求助]

mars

谢谢！！！
     1. (The average), people who have asthma hear better than those (who don't), and scientists are not sure9 why) this( is so).
key: a

     2. The tar and other (irritants) in cigarettes lead to the( scarring) and (accumulation) of problem in the lungs and the branchial tubes( lead) to lung.
key: d

     3. The Nutlarbor Plain,( located)( along) the southern coast of western and southern australious is( probable) the area( with) the largest source of meteorites.l
key: c

     4. Many scientists believe____ is mainly a way the body uses to rid itself of chemicals prouduced by emotional stress.
     a) babies cry    b) that babies cry    c) the crying of babies   d) babies crying
key: c                how about b ?

    5. The Atlantic Ocean is___ salty and , an average, saltier than the Pacific Ocean mainly because of the deposits found off many of its coastlines.
    a) usually fair  b) a usually fairly  c) usually fairly  d) a usual fair
key: c                  how about a ?

    6. Because the body must,( within) every second, transfer about 100 million messages to your brain, millions of active (sense) nerves are required to( sent) messages in any( given) moment.
key: a                 how about c ?

    7. The length of a radio wave is( measuring) from crest to crest, form the tip of (one) wave to the tip of the next, and this is (now) we distinguish them, (as) well.
key: a

    8. An experiment is a kind of harmless trial run of some actions to make some sense of the( real) world, which can (either) made in the laboratory or( by) observing fox-cubs outside (their) home.
key: b

mars

Thank you very much!!!