Вопрос по английскому языку:

Помогите пожалуйста!!
1.I am busy at the moment. I ... on the computer.
a)work b)have worked c)am working d)have working
2.Let's begin now. We ... long enough.
a)are standing b)have been standing c)stand d)have stood
3.Tom always ... tennis on Monday.
a)play b)is playing c)plays d)has played
4.It's nine o'clock. The students ... a lesson.
a)have b)have had c)has d)are having
5.They ... us several telegrams latery.
a)send b)have send c)are sending d)have been sending
6.I wonder why John ... a job yet.
a)Finds b)didn't find c)hasn't found d)found
7.Listen! If ... heavity.
a)rains b)has been raining c)has rained d)is raining
8.Every day they ... their dinner at the canteen.
a)have b)has c)are having d)have had