——_________ is he going to be after he leaves school?
——He's going to be a doctor.
A:Who
B:What
C:Which
D:Why
小明和小张两人练习电脑打字,小明每分钟比小张少打6个字,小明打120个字所用的时间和小张打180个字所用的时间相等。设小明打字速度为x个/分钟,则列方程正确的是( )
①没有给试管均匀受热; ②试管外壁潮湿; ③试管口没有略向下倾斜;
④忘了加棉花; ⑤加热时试管底部与灯芯接触; ⑥收集完氧气,先撤酒精灯.