—Is this your hat?
—________. [ ]
A. Yes, it is
B. Yes, it isn't
C. No, this isn't
答案:A
一件服装,先涨价10%,再降低10%,则现价比原价[ ]
A.提高了
B.降低了
C.无法确定
D.不变
闪电后4秒钟听到雷声,问:闪电处距观察者有多远?(V声=340米/秒,V光=3×108米/秒)