burn the midnight oil 开夜车

to work hard very late into the nightand as if working only by the light of an oil lamp

EXAMPLE:

s ambitious new product.

A square deal 公平交易

a fair and honest business agreementorarrangement between twoormore parties without false promisesorhidden surprises

EXAMPLE:

After many hours of negotiations the musicians， the music publishers and the Internet companies developed a distribution agreement that everyone felt was a square deal.

Ace in the hole

秘藏的法宝

a hidden advantage kept for later use that will help a person win ; alternatively， an ace up your sleeve

EXAMPLE:

When he tried to get a job at the XYZ Corporation， John did quite well in the rigorous interview process， but he knew that his ace in the hole was the fact that his wife had a relative on the board of directors.