better off

1．trade-off(between sth.and sth.)

：the act of balancing two thngs that you need or want but which are opposed to each other.

（在需要而又相互对立的两者之间）权衡

There is a trade-off between the benefits of the drug and the risk of the side-effects.

这种药的疗效与副作用之间有个权衡利弊的问题．

trade：the activity of buying and selling（买卖）

the arms trade 军火贸易

2．better off

be better off ：to have more money（比较宽裕）

Her promotion means that she is 100 dollars a week better off.

她的晋升相当于每月工资增加100美元．

better （good 的比较级）

You'd be better going by bus.你坐公交车去会好点．