下列各组句子中加横线的词，解释全部正确的是（ ）

Don’t be afraid of asking for help ______it is needed.

Wish you good luck in the exam.– .Thesame to you.A．Me, too

Jackie would like to buy an iphone 5 but _____ wasavailable from that shop.

The boss wants to keep his shop _______ for another three hours.