به نام خدا

Absence makes the heart grow fonder :دوری و دوستی

This idiom means that when people are apart, their love grows stronger.

Accident waiting to happen: اتنظار اتفاق ناگوار آن اتفاق را پیش می آورد

If something is an accident waiting to happen, there's definitely going to be an accident or it's bound to go wrong. ('Disaster waiting to happen' is also used.)

Ace in the hole: برگ برنده

An ace in the hole is something other people are not aware of that can be used to your advantage when the time is right.

Ace up your sleeve: برگ برنده

If you have an ace up your sleeve, you have something that will give you an advantage that other people don't know about.

Achilles' heel : نقطه ضعف

A person's weak spot is their Achilles' heel.

Acid test:     سنگ محک

An acid test is something that proves whether something is good, effective, etc, or not.

Across the board

If something applies to everybody, it applies across the board.

Across the ditch : آن سوی آبها

(NZ) This idiom means on the other side of the Tasman Sea used to refer to Australia or New Zealand depending on the speaker's location.

Across the pond: آن سوی آب

(UK) This idiom means on the other side of the Atlantic Ocean, used to refer to the US or the UK depending on the speaker's location.

Act of God : کار خداست و کاری از دست ما ساخته نیست

An act of God is something like an earthquake or floods that human beings cannot prevent or control.

Act of war: جرقه ی جنگ افروزی

An act of war is a action that is either intended to start a war or that is interpreted as being sufficient cause for a war.

Actions speak louder than words: دو صد گفته چون نیم کردار نیست

This idiom means that what people actually do is more important than what they say- people can promise things but then fail to deliver.

Add fuel to the fire: هیزم به آتش جنگ افزودن

If people add fuel to the fire, they make a bad situation worse.

Add insult to injury : هیزم به آتش جنگ افزودن

When people add insult to injury, they make a bad situation even worse.

After your own heart : هم فکر بودن

A person after your own heart thinks the same way as you.

Against the clock : بسیار عجله داشتن

If you do something against the clock, you are rushed and have very little time to do it.