1.you can only pass this exam by studying hard 

only

2.you can only understand it when you grow up 

only

3.I can only realized that I'd seen it before after the film started

only

4. the exercise is so easy that every students can do it easily

not only

5.he not only studies well , but also he sings well

so

6.If you meet her , please call me 

should 

7. If you had obeyed orders this diaster would not have happend

had

1.she had never experienced this exhilarating emotion in her life                           never                                                                                                             2. he has seldom seen anything stranger 

  seldom 

3. I have seldom seen him looking so miserable

seldom

4. as soon as I had got out of the bed , the phone rang

scarcely

5.as soon as he had finished dinner , she walked in the door

no sooner 

6. I only understood the problem then

only

7. we will be only  able to accomplish thí great task by working hard

only