On Screen B2 Crime 3 test questions
Hello!

I've made 3 mistakes. Still, I am not sure what correct answers are. Here is the screenshot to understand what I am talking about: https://ibb.co/vvDGgwd

Complete the second sentence so that it has a similar meaning to the first sentence. Do not change the word given. You must use two to five words, including the word given. Here is an example (0).

0 Lisa regretted leaving the door unlocked. WISHED
Lisa wished she had locked the door.
1 With a proper security system, the burglary could have been prevented. THERE
The burglary could have been prevented...............................a proper security system.

3 I’m not sure who that wallet belongs to. WHOSE
I’m not sure .......................................................is.

6 The firemen found it difficult to control the fire with such a strong wind blowing. UNDER
The firemen found it difficult to .................with such a strong wind blowing. (Taken from On Screen B2 by Virginia Evans)Could you explain what's wrong with my answers?

Question

On Screen B2 Crime 3 test questions
Hello!

I've made 3 mistakes. Still, I am not sure what correct answers are. Here is the screenshot to understand what I am talking about: https://ibb.co/vvDGgwd

Complete the second sentence so that it has a similar meaning to the first sentence. Do not change the word given. You must use two to five words, including the word given. Here is an example (0).

0 Lisa regretted leaving the door unlocked. WISHED
Lisa wished she had locked the door.
1 With a proper security system, the burglary could have been prevented. THERE
The burglary could have been prevented...............................a proper security system.

3 I’m not sure who that wallet belongs to. WHOSE
I’m not sure .......................................................is.

6 The firemen found it difficult to control the fire with such a strong wind blowing. UNDER
The firemen found it difficult to .................with such a strong wind blowing. (Taken from On Screen B2 by Virginia Evans)Could you explain what's wrong with my answers?

Answer

1.  They're looking for a full third conditional,  '..if there had been..'.   
In spoken English, you could probably get away with 'if there was', especially if there still isn't one in place at the time of speaking.  It isn't quite right, though. You ought to use a third conditional for a hypothetical situation in the past.

3.  Your answer is a valid alternative, I think.

4.  It ought to be 'get', because this is an action. You need a dynamic verb. 'Have the fire under control' describes a state.

Answer

As Su. Ki. says your answer to #3 is an alternative.

The expected answer "... whose wallet that is"  uses "whose" as a possessive determiner (the most common case).  Your answer uses "whose" as a possessive pronoun (less common).

whose wallet that wallet is <<== full form
whose wallet that [wallet] is <<== expected answer, whose acts as a determiner
whose [wallet] that wallet is <