Present perfect continuous , deduction about past

 Present perfect cont/ present perfect/ obligation / deduction

I have done                       I have been doing

I had to do it                    I must have done it

Probably – I might                               obligation – I had to

I am sure – I must                                I am sure not – I can’t

1. I ( stand) .......................here for 20 minutes. She is late. I am not sure,  but she ( forgot) .........................................about our meeting.

2. I ( learn) ...........................for 2 hours,  I ( not learn) .................much. Mark got 5 in the test and he is not as good as I am. I am sure, he ( cheat) .............................on the test.

3. I ( learn) .........................yesterday because I had a test today in the morning. It was really difficult.  I am not sure but I ( get) ................all the result wrong, it is just a hunch. This term I ( fail) ..................all the tests so far. 

4. He is not there , probably he mistook the address. He ( mistake).....................the block numbers, I think. I ( invite) ...................him 5 times this year to my apartment, yet he keeps forgetting the address. Yet, we (know).........................each other for almost a year now. 

5. I am worried as I ( lose) ....................my keys as I can't see tehm anywhere. .................you .............(see) them anywhere? I ( look) ...................for them for hapf an hour now. Yes, I know now ! I ( leave) ..................them at work. I ( have to) ..................stay longer and I was so tired. 

6. She ( cheat not) ………………..I am sure she didn’t as I know that she ( learn) ………………………a lot recently.