1.ace作“擅长…的人”解时指的是在某方面超群的人,其后常接介词at。
2.ace作“发球得分”解用于网球或排球运动中,指因对手接不到发球而得分。

an ace up one's sleeve
秘藏的王牌; 应急的妙计; 锦囊妙计a secret or hidden advantage that you can use when you need it
〔说明〕 本短语是英式英语,美式英语是an ace in the hole。
He thinks he's won but I've got an ace up my sleeve. 他以为他赢了,但我自有取胜的妙招。

hold all the aces
〔说明〕 本短语还可说have all the aces。占尽一时地利人和have all the advantages in a situation
It was a battle of wits, with Sandra holding all the aces. 那是一场智斗,桑德拉占尽了上风。

play one's ace
打出王牌; 使出绝招use your best argument, etc., in order to get an advantage in a situation
Many pretty girls played their ace.许多漂亮姑娘都使出了绝招。

within an ace of
〈英·非正〉差一点儿; 几乎 very close to (a condition); almost doing sth, or nearly succeeding in doing it
▲within an ace of sth
We were within an ace of success. 我们差点儿就成功了。
We came within an ace of victory. 我们差一点儿就要胜利了。
▲within an ace of v-ing
He came within his ace of being run over. 他险些被车子从身上碾过。

In card games, the ace often has the highest number of points. 在纸牌游戏中,A牌常代表最高分数。
He was a flying ace in the First World War. 他是一战时的飞行专家。
She served and got an ace.她发球并得分。
He served 15 aces in the match. 他在这场比赛中发球得分15次。
▲～+prep.-phrase
He's an ace at baseball. 他是位优秀的棒球选手。
She's an ace at tennis. 她是一个网球能手。
Tom is an ace at cards.汤姆是玩牌高手。
▲～+that-clause
That's the third ace that Violente has served this match. 那是瓦奥兰特在这场比赛中的第三次发球得分。

ace用作形容词时意思是“第一流的”，在句中可用作定语或表语，不用于比较等级。

用作定语
▲～+n.
That's an ace bike you've got there. 你那辆自行车是一流的。
We had an ace time. 我们过得真痛快。
用作表语
▲S+be+～
Their new record's really ace! 他们新灌的唱片真是没得说！
Their new song is ace! 他们的新歌太棒了！