that all the risks should be calculated in advance. A: This is necessary B: Which is necessary C: That is necessary D: It is necessary

We consider _____ lessons should be previewed before the class. A: that it necessary B: it that necessary C: it necessary that D: necessary it that

I find ____________ to make some changes. A: it is quite necessary B: that is quite necessary C: it quite necessary D: quite necessary

If_____, we’ll continue our experiment after office hours. A: being necessary B: be necessary C: is necessary D: necessary

101×59的简便运算是 A: （100+1）+59 B: （100×1）×59 C: 100×59+1×59

“优酷定向流量产品”订购后有效期是多久（） A: 2018年7月31日23：59：59失效 B: 2018年8月31日23：59：59失效 C: 2018年9月31日23：59：59失效 D: 2018年10月31日23：59：59失效

If_____,<br/>we’ll continue our experiment after office hours. A: being necessary B: be necessary C: is necessary D: necessary

We consider ____university students should do more reading during their spare time. A: necessary that B: necessary C: it necessary D: it necessary that

59的原码是_______________________-59的反码是______________________.-59的补码________________。

下面说法正确的是（ ）。知识点：列表->字符串 A: time = [23,59,59]print(":".join(time))的输出结果是23:59:59 B: time = ['23','59','59']print(":".join(time))的输出结果是23:59:59 C: time = ['23','59','59']t_str = ""for t in time: t_str += t+":"print(t_str)程序输出结果是23:59:59 D: time = [23,59,59]t_str = ""for i in range(len(time)): if i<len(time)-1: t_str += str(time[i])+":" else: t_str += str(time[i])print(t_str)程序输出结果是23:59:59