back up 支持

A：I agreed to your proposal at the meeting this morning. It was a good one.

B：You should have backed me up then when I needed it.

A：The matter was too complicated to explain.

A：我同意你今天早晨在会上的建议，建议很好。

B：那么你就应该在我需要的时候支持我的。

A：事情很复杂，不太好解释。