It's difficult for them to get here much before seven.

他们很难在7点以前早早地来到这里。

Two plus five is seven.

二加五等于七。

You should receive a reply within seven days.

你会在七天之内收到答复。

The ticket gives you unlimited travel for seven days.

凭本车票在七日内可自由乘车不受限制。

Seven from ten leaves three.

10减7得3。