Put the verbs in brackets into the correct present/past perfect tense 1. I'm afraid the exhibit (remove) for cleaning so you can't see it today
2. I (not/hear) of a market before I visited the museum
3. How long (Luke/read) that book about ancient Egypt?
4. He was tired yesterday evening because he (dig) at the archaeological site all day
5. (you/finish) your research yet?
6. The stars (use) by sailors to navigate the seas for centuries by the time the compass was invented​

1. I'm afraid the exhibit has been removed for cleaning so you can't see it today.
Explanation: We use the present perfect tense here because the action of removing the exhibit happened in the past but has a result or consequence in the present (the exhibit is not available today).

2. I had not heard of a market before I visited the museum.
Explanation: We use the past perfect tense here because the action of hearing about the market (or not hearing about it) happened before the action of visiting the museum in the past.

3. How long has Luke read that book about ancient Egypt?
Explanation: We use the present perfect tense here because we are asking about the duration of time from the past until now in which Luke has been reading the book.

4. He was tired yesterday evening because he had been digging at the archaeological site all day.
Explanation: We use the past perfect tense here because the action of digging at the archaeological site happened before the action of feeling tired in the past.

5. Have you finished your research yet?
Explanation: We use the present perfect tense here because we are asking about the completion of the research up until now.

6. The stars had been used by sailors to navigate the seas for centuries by the time the compass was invented.
Explanation: We use the past perfect tense here because the action of using the stars for navigation happened before the action of inventing the compass in the past.