A．An investigation into how Americans spend their vacations.

B．An opinion poll of how people should spend their leisure time.

C．A poll of how employed Americans spend their leisure time.

D．A report on the vacation plans of college graduates in America.

有自觉的目的，但不需要意志努力的注意是（）。

A、有意后注意；

B、有意注意；

C、无意注意；

D、以上一个也不是。