— Who will go to the airport to meet Mary?
— I will. I ________ her several times. I can find her easily.
A:met
B:have met
C:had met
D:will meet
若式子x-7在实数范围内有意义,则x的取值范围是( )
I spend an hour____ (do) my homework in the evening.
日常生活中使用燃气时出现了以下现象,我们应探究原因并想办法解决.
用显微镜观察小鱼尾鳍内的血液流动情况时,红细胞只能单行通过的血管是( )