1. The fire ___ due to faulty insulation. But, for the time being, we cannot exclude a terrorist attack. A. may have started
B .might be started
C. could start
D. must have started
2. They to the concert together because Jane had agreed to baby-sit for them.
A. could go
B. could have gone
C. were able to go
D. can go

I don't know the difference ''could '' and ''were able to go ''. Can you help me??​

1=A, 2=C

Explanation:

the present continuous is a verb tense which is mainly used to indicates that an action is in progress at the moment of speaking.  

it is formed using: person + verb to be (am/is/are) +verb + - ing form  

example: i am studying at this moment .

in addition, the present continuous is also used in order to express things that will or will not happen in the near future.

example: i am having dinner with some friends tonight.

the speaker sometimes   uses it   to express that an action is repeated and it causes irritation on the part of the speaker

example: my sister is constantly complaining about everything.

honestly you should not write it the word placement is not right and this does not sound right so i think you should write it this way. the life lessons i refused to learn, taught me the hard way this sounds way better you should try it! hope this is very !