I-I know what I'm supposed to do,我知道该怎么做

be supposed to猜想会； 应该

The ghost of Lady Margaret is supposed to haunt this chapel.

据说玛格丽特女士的鬼魂常在这个礼拜堂出没。

The details were supposed to be secret but somehow leaked out.

这些细节原属秘密，可是不知怎么给泄露出去了。

and if I don't hear from you by tomorrow,如果明天还没有收到你的回复

hear from接到 ... 的信

When they did not hear from her, they feared the worst.

他们那时听不到她的消息，唯恐发生了最糟的事。

I hear from my cousin every two months.

我每两个月就会收到我表哥的来信。

This woman has the power to destroy everything you can mean to do.这女人有能力毁掉你所有企图

mean to打算

I didn't mean to take a taxi but I had to, as I was late.

我虽然不想坐计程车，但因为太迟了所以非坐不可。