问题
Usually pilots need about a decade of experience _______ they can be promoted to captain
A:after
B:before
C:then
D:when
B:before
C:then
D:when
正确答案是：
同类题型
ina,we’re going to Sam’s house to celebrate his graduation. Would you like to—Great!Let’s go.
1—I’m going to Sanya for myholiday tomorrow. —_______
Mary,along with her parents ______Hainan for a weekand they will come back soon.
confident,_____ , in my opinion, is themost important in society result of cancer