A. Modifiers do not affect the number of the verb.

- The teacher, along with his students, wants to play soccer.
(The phrase “along with his students” is a modifier.)

B. Expressions of time, distance, price, and weight need a singular verb.
- Ten dollars is too much for a lunch.

C. In case of fractions or their equivalents, the noun in the of-phrase determines the number of the verb.
- Two-thirds of the land has been sold.

D. The number of the verb is determined by what is next to it in sentences with either A or B, or neitherA nor B.
- Either he or his pupils are going to help us.

Note: When the subject begins with not only A but (also) B or B as well as A, the number of the verb is determined by B.