APU火警导致APU关车，在起飞至1500ft以下是被抑制此警告的
参考答案：对
—How long _______ you _______ the bicycle?
—About two weeks. [ ]
A. have, had
B. have, bought
C. did, buy
D. have, have
().
A．发散
B．条件收敛
C．绝对收敛
D．无法判定敛散性
().