下列函数中，函数值恒大于零的是（） (A)y=x2 (B)y=2x (C)y=㏒2x (D)y=cosx

A. is in a bad mood
B. has the bad temper
C. has the bad humour
D. has lost his mood

A. how to make the best useof leisure time
B. planning our timescientifically
C. the modern pace
D. our interest in shortenedoperas

A. has undergone
B. undergoes
C. underwent
D. had undergon

A. {x
B. x＞3}
C. {x
D. -1＜x＜2}
E. {x
F. 2＜x＜3}
G. {x
H. 1＜x＜2}