—WhydidMikeignore(不理睬)mecompletelywhenIsaidhellotohim?—...

問題詳情：

—Why did Mike ignore (不理睬) me completely when I said hello to him?

—Oh, he was keeping ________ a problem.

A．think about            B．to think about

C．to thinking about   D．thinking about

【回答】

D

知識點：動詞和動詞短語

題型：選擇題