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。