Could vs (be) able to.

Hi everyone,

In the following multiple choice question, the answer is B, but can you differentiate for me “could” and “(be) able to”?

1. Robert has a new car. He … it for a very good price. He paid 30% less than the regular retail cost.
a. could buy b. was able to buy c. was supposed to buy d. had to buy

I have another sentence but it’s not correct one, could you please help me correct it and tell me why?

2. A million of tourists from all over the world visit NY every year.

I also have problems with prepositions. In these 2 sentences, I have no idea about the answer, can you show me which prepositions should be there and why?

3. It’s high time Bill got a steady job and settle … He is almost 30.
4. It’s difficult to tell identical twins …

Finally, I have no idea which word should be used in this situation, help me pls.

5. Sarah delivered a(n) … appeal to the court and asked for mercy
a. sensational b.sentimental c. emotional d. affectionate

The answer is C, but I suppose it A.

Many thanks,
.
HuongAn

Look at my suggestions:

  1. He was able to buy it for a very good price
  2. A million tourists from all over the world visit NY every year.
  3. It’s high time Bill got a steady job and settled in life.( you sentences require more info.)
  4. It’s difficult to tell identical twins apart (by looking at their faces.)
  5. Sarah delivered an emotional appeal to the court and asked for mercy.

best of luck,
nanucbe