If you wish to call a phone both easily and inexpensively, you have to know the （）and the phone number.
举一反三
- I (call)____you earlier if I (lose/not) ____your phone number.
- I wish I ______ you, but I don't know his phone number. A: can help B: can have helped C: could help D: could have helped
- If you need to know a phone number, look it up in the phone ........ A: directory B: list
- If you have problems with a phone, you call the... A: telephonist B: operator
- If you want to phone him, you’ll have to ____the number in the book first.