【简答题】Task 1. Listen to a conversation and complete the following sentences with the words you have heard. You should write no more than three words. I know my job very well but feel I don’t fi t well in wi...
【简答题】给出下列四个命题: ①命题“? x ∈R,cos x >0”的否定是:“? x ∈R,cos x ≤0”; ②若lg a +lg b =lg( a + b ),则 a + b 的最大值为4; ③定义在R上的奇函数 f ( x )满足 f ( x +2)=- f ( x ),则 f (6)的值为0; ④已知随机变量 X 服从正态分布 N (1, σ 2 ), P ( X ≤5)=0.81,则 P (...