I wasn't born yesterday.

我又不是三岁小孩。

Just to be on the safe side.

为了安全起见。

Everything will be fine.

一切都会很好。

He is now out of touch with his old friends.

他现在已经没有和他过去的朋友联系了。

I look forward to receiving your reply.

我期待着你的答复。

Can you imagine what it would be like to live without electricity?

你能想象出生活中没有电会是怎么样的一种情形吗？