关头的英文：
juncture
moment

参考例句：

a critical juncture; a critical moment
关头

A last-minute entry for the pony race.
最后关头才参赛的马。

That is a critical moment.
那是生死存亡的关头。

You must keep calm in an emergency.
在紧急关头要保持镇静。

At this juncture
在这重大关头,值此际

He's the sort of man you can't reckon on in a crisis.
他是一个在紧急关头靠不住的人。

The situation was then about to boil over.
当时形势即将发展到紧急关头。

You must keep calm (cold) in an emergency.
在紧急关头要保持镇静(冷静)。

He saved his strength for an effort in the last minute of the race.
他将力气保留准备在赛跑的最后关头作冲刺。

He let me down at the last minute and turned out to be a broken reed.
他在紧急关头拆了我的台,成了背信弃义的人。

juncture是什么意思：
n. 关键时刻；连接；接缝

a critical juncture; a critical moment
关头

And at the most critical juncture we took turns in watching that point.
在最紧急的时刻，我们轮流监视那段河流原险情。

On my conduct at the present juncture my whole future depends.
我的前程都取决于我在这个时刻的表现。

We generally use white latex as wood juncture of binder.
我们一般都使用白乳胶作木制品接缝的粘结剂。

The direction of place of ceramic tile juncture is fore-and-aft.
瓷砖接缝处的方向是纵向的。

moment是什么意思：
n. 片刻，瞬间；时机；重要；力矩，矩

at this exigent moment
在此危急关头

On the spur of the moment
一时冲动

stalling moment
失速力矩|使气流离体力矩

He relaxed for a moment.
他浑身放松了一会。

At the very moment, there was a loud crack.
就在那一刹那，突然传来一阵巨大的爆裂声。