――Excuse me，could you tell me if there is a hospital near here? ――＿＿＿＿ A.Yes，why not． B.no，I couldn't． C.Sorry，I'm a stranger here myselF.D.My pleasurE.

单项选择题将超声波转换成电信号，是利用压电材料的（ ）。 A、应变效应 B、电涡流效应 C、压电效应 D、逆压电效应

单项选择题――I'm afraid I can't finish the book within this week．――＿＿＿＿ A.Please go aheaD.B.That's right． C.Not at all． D.Take your timE.