无码高清视频|成人自拍视频|欧美成人午夜无码A片秀色直播|草美女视频网站|美女被操网站在线观看

單項選擇題

When the starting air valve closes on one cylinder, another starting air valve has () opened on another cylinder whose piston has just commenced its downward stroke.

A.just
B.nearly
C.merely
D.already

微信掃碼免費搜題