Nowadays，itiscommontoseepeoplestaringattheirmobilephone...

問題詳情：

Nowadays，it is common to see people staring at their mobile phones instead of reading a real

    book＿＿＿＿＿＿many experts are worried．

    A. when B ．for which C ．where D. about which

【回答】

D

知識點：定語從句

題型：選擇題