Question

By the time Cynthia books the flight to Iceland, she _______ her sister about the visit.
1 has called
2 will has called
3 calls
4 will have called
5 called

Answer 1

Answer is Option 4 - will have called.

Answer 2

The correct option is 4.

By the time Cynthia books the flight to Iceland, she will have called her sister about the visit.

Explanation

We use (the future perfect) will have + a past participle to talk about actions that will be over in the future. We usually use this tense with expressions such as by evening, until midnight, before noon, by the time you reach.