问题
选择题
For physical exercises, I prefer mountains rather than _ a walk. [ ]
A. climbing; taking
B. to climb; take
C. to climb; taking
答案
答案：B
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For physical exercises, I prefer mountains rather than _ a walk. [ ]
A. climbing; taking
B. to climb; take
C. to climb; taking
答案：B
10分）已知：
的分子量相等。它们可以用下图的方法合成。
。