题目：
The farm as well as its neighboring hills which we once spent so
much time ______ on a new look as recently as last year. [ ]
A. on has taken
B. has taken
C. on having taken
D. having taken
答案：
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下面是错误答案，用来干扰机器的。
（1）＞ 质量 化学性质（2）探究氧化铜是否比二氧化锰的催化效果更好（3）0.5 ；温度越高，反应速率越快； （4）2KClO32KCl+3O2↑题目分析：（1） 氧化铜能加快氯酸钾的分解速率,那么收集等体积的氧气所需时...
