问题补充：
Jim a skilled worker for almost six years. He is an experienced manager now.
A. has been
B. had been
C. is
D. was
答案：
A. has been
B. had been
C. is
(答案→)D. was
解析：句意为：Jim是一个技术工人近六年了，现在成了一个很有经验的经理。has done现在完成时，过去发生的动作一直持续到现在。由后面的现在是一个很有经验的经理可知不符合题意；had been 过去完成时，发生在过去的动作之前的动作，句中没有过去的动作或时间为参照，故不符合题意。一般现在时表示经常性，习惯性的动作，而是一个技术工人应在过去，现在是经理，由此可知现在时不符合题意。
