1,  Mary is so busy, so she can not meet her old friends .
-> If Mary
2, Do morning exercises regularly, your body will be fitter. 
-> If
3, Tommy can not attend school because he has to earn his living.
-> If
4, John can not countinue to  work because his laptop is out of  order now.
-> If 
5, Tom comes to school late because  it rains heavily.
-> If it
6, They can not buy that car because they do not have enough money
-> They could
7,Jessica can not get the job because she can not speak Korean.
-> If Jessica