11. A significant proportions of the plants and animals of Hawaii exists nowhere
a b c
else in the world.
d
答案： A
解析： 注意到句首的“a”,所以这里用单数形式，改为：proportion.
12. You will not be able to pass your examination except you study harder than you
a b c
do now.
d
答案： B
解析： 表达“除非”的意思；except 改为unless。
13. Some bosses dislike to allow people to share their responsibilities; they keep
a b
all important matters tightly in their own hands.
c d
答案： A
解析： dislike doing sth. 指“不喜欢做…”。
14. Generally speaking, the bird flying across our path is observed, and the one
a b
staying on the tree near at hand is passed by without noticed.
c d
答案： D
解析： without是介词，后面应该接名词或动名词，同时，该句又是被动的含义所以应改为: without being noticed.
15. On the whole, ambitious students are much likely to succeed in their studies
a b
than those with little ambition.
c d
答案： B
解析： 此句是一个包含了比较级的句子，所以B项应改为： are more likely.
