问题
选择题
Though iPhone 4 is such a hit product, I won’t buy one unless its after service ______.
A．was improved
B．gets improved
C．is improving
D．had got improved
答案
答案：B
主句I won’t buy one用的是一般将来时态，所以unless引导的条件状从要用一般现在时表将来；且its after service和improve的动宾关系，所以用一般现在时态的被动语态。选B。