Please help me with this question about tense.
I've got a question about tense. It's from an high school English test.
I really am confused.
They say that there are two wrong tense out of those five ones in this sentenses.
A man who operated an icehouse lost his good watch in the sawdust.
He ■(offered) a reward, and several men went through the sawdust with rakes.
But they were not able to find the watch.
When the searchers ■(left) the building for lunch, a small boy went into the icehouse.
A few minutes later he came out with the watch.
They asked him how he ■(had found one).
He replied, "I just ■(laid down) in the sawdust and listend.
Finally I heard the watch ■(ticking)."
a. offered
b. left
c. had found one
d. laid down
e. ticking
I only found out that (b) is wrong and it should be like this : "had left"
Do you agree with my correction?
Well, I don't think there are one more thing besides "b"
Could you please help me find one left?