【简答题】是否存在x,使得当a=2时分式 的值是0。
【简答题】酶的化学修饰方法主要有______、______、______和______。
【单选题】_______, Mr. Wells is scarcely in sympathy with the working class.
A.
Although he is a socialist
B.
Even if he is a socialist
D.
Since he is a socialist
【简答题】已知数列 满足 , , ,其中 是给定的实数, 是,试求 的值,使得 的值最小.