【简答题】Read the following sentences and decide whether they are true (T) or false (F). Point out the fine sentences. 1. The man who had been standing by the door when she arrived. 2. Exhausted, the traveler ...
【简答题】On a hot summer holiday, a little boy decided 1 (go) for a swim in the lake behind his house. He jumped into the water, not realizing a crocodile was 2 (swim) towards him. In the house, his mother...
【简答题】有下列命题: ①函数y=4cos 2x,x∈[﹣10π,10π]不是周期函数; ②若点P分有向线段 的比为λ,且 ,则λ的值为﹣4或4; ③函数y=4cos(2x+θ)的图象关于点 对称的一个必要不充分条件是 ; ④函数y= 的最小值为2 ﹣4 其中正确命题的序号是( )
【多选题】加油站的作业事故发生火灾的主要时段为( )。
【单选题】有一段演绎推理是这样的:“三角函数是周期函数, 是三角函数,所以 是周期函数.”在以上演绎推理中,下列说法正确的是( )
【简答题】定义在 上的函数 不是常数函数,且满足对任意的 , , ,现得出下列5个结论:① 是偶函数,② 的图像关于 对称,③ 是周期函数,④ 是单调函数,⑤ 有最大值和最小值。其中正确的命题是 ( ) A ①②⑤ B ②③⑤ C ②③④ D ①②③