Possessives/Fill in the gaps

For each of the following sentences, fill in the blank with either the singular or the plural verb form shown in brackets. Be prepared to explain why the form you have chosen is correct. For example:

The committee ____ put forward a new proposal. (has, have)
The committee has put forward a new proposal.
In this example the committee is acting as a whole. Therefore a singular verb is used.

The committee ____ disagreed on what policy to adopt. (has, have)
The committee have disagreed on what policy to adopt.
In this example, the members of the committee are acting as individuals. Therefore a plural verb is used.

Two tons of coal __ required. (is, are)
Two tons of coal is required.
In this example, the amount two tons is considered as a whole. Therefore a singular verb is used.

1. The crew ______ preparing the ship to go to sea. (is, are)
2. The crew ______ different levels of experience. (has, have)
3. Two pounds of butter _____ too much. (is, are)
4. The class _____ not agree on what should be done. (does, do)
5. The class _____ contributed eighty dollars to the cause. (has, have)
6. Three ounces of gold _____ worth more than three ounces of copper. (is, are)
7. The group _____ decided to hold a meeting once a month. (has, have)
8. The group _____ varied backgrounds. (has, have)
9. Fifty cents _____ the regular price. (was, were)
10. Six dollars _____ been collected. (has, have)