单项选择题
The pilot is on board,（） ?
A.is it B.isn't it C.is he D.isn't he
单项选择题 The iron mike is a(n) （）.
单项选择题 The first indications a mariner will have of the approach of a warm front will be （）.
单项选择题 The characteristic of a lighted cardinal mark may be （）.
