你必须按时吃药，医生说的。

You ___must take your medicine on time, as the doctor said.

他连续工作了12个小时，现在一定很累了。

He's been working for 12 hours straight—he ___must be exhausted now.

如果你非要问的话，是我把遥控器弄丢的。

If you ___must ask, I was the one who lost the remote control.

你一定要尝尝我做的苹果派。

You ___must try my homemade apple pie.