O-7:on the level 诚实无欺
A:I tried to return your novel this afternoon. But there is nobody at home.
A：我今天下午去你那儿还书，但你家没人。
B:Why didn't you leave it next door?
B：你为什么不把它放在隔壁呢？
A:But I didn't know them very well.
A:我对他们不了解。
B:They're on the level. You can trust them.
B:他们诚实可靠，你可以相信他们。
