It's difficult for them to get here much before seven.
他們很難在7點以前早早地來到這里。
Two plus five is seven.
二加五等于七。
You should receive a reply within seven days.
你會在七天之內收到答復。
The ticket gives you unlimited travel for seven days.
憑本車票在七日內可自由乘車不受限制。
Seven from ten leaves three.
10減7得3。