.His mother taught him _______ and read. [ ]
A. write
B. writing
C. to write
D. writes
答案:C
图所示天气系统是
A.冷锋
B.暖锋
C.准静止锋
D.低压
标准正态分布的均数和方差分别为()
A.0和0
B.1和0
C.0和1
D.1和1
E.以上都不对