当活塞上死点,缸内()压力仍高于大气压力,排气门迟关一些,可使废气排得干净些。
A、空气
B、废气
C、可燃气体
D、二氧化碳
参考答案:B
海面有A,B,C三个灯塔,AB=10km,从A望C和B成60°的视角,从B望C和A成75°的视角,则BC=______km.
—I really don't know what I ________yesterday without the bike you lent me.
—Glad to have been some help to you.
A.could do
B.should have done
C.had done
D.could have done