suffer
受损害，受到不良影响  

例句：
Your studies will suffer if you play too much football.
如果你总是踢足球，你的学业就会受到影响。

under the cover of...
在……的掩护下；以……为借口
 
例句：
The troop withdrew¹ safely under the cover of darkness.
军队在夜幕的掩护下安全撤离了。
 

I'll pick up the tab.
我来付帐。

对话：
A: Do we have to pay the transportation fee?
B: No. This trip is on me. You don't have to spend a penny. I'll pick up the tab.
A: How generous you are.

A：我们得付交通费吗？
B：不，这次旅行我请客。你们不用花一分钱。我来付费。
A：你真慷慨。