Complete the sentences with the modal verbs below: can/can't/could/couldn't /wasn't able to, may/might or have to/had to. 1. people write e-mails until 1990. since then they have written billions of them. 2. unfortunately, i really program at all. no-one among my friends is a programmer either. 3. i send my e mail from yahoo mail. there were some problems with the server. 4. the first computers only do simple math formulae like addition and subtraction. 5. with a reference management software on your computer at the end of a lengthy assignment you have more than 100 links. 6. the first programmers face grueling hours of counting and calculating to get operations done.
2. can't
3. wasn't able to
4. could
5. might
6. had to