1.a long narrow opening

2.a narrow opening;

he opened the window a crack

3.a long narrow depression in a surface

4.a sudden sharp noise;

the crack of a whip

5.a chance to do something;

he wanted a shot at the champion

6.witty remark

7.a blemish resulting from a break without complete separation of the parts;

there was a crack in the mirror

8.a purified and potent form of cocaine that is smoked rather than snorted

9.a usually brief attempt;

he took a crack at it

10. the act of cracking something

11.of the highest quality;

an ace reporter

1.become fractured; break or crack on the surface only;

The glass cracked when it was heated

2.make a very sharp explosive sound;

His gun cracked

3.make a sharp sound;

his fingers snapped

4.hit forcefully; deal a hard blow, making a cracking noise;

The teacher cracked him across the face with a ruler

5.pass through (a barrier);

Registrations cracked through the 30,000 mark in the county

6.break partially but keep its integrity;

The glass cracked

7.break suddenly and abruptly, as under tension;

The rope snapped

8.suffer a nervous breakdown

9.tell spontaneously;

crack a joke

10. cause to become cracked;

heat and light cracked the back of the leather chair

11. reduce (petroleum) to a simpler compound by cracking

12. break into simpler molecules by means of heat;

The petroleum cracked

1.I wish Jill wasn't such a tough nut to crack.

我希望吉尔不是个那么难打交道的人。

2.This problem is a tough egg to crack.

这一问题可真令人难以理解。

3.Getting them all here on time will be a tough nul to crack.

要他们全都准时到将是件很难办到的事。