One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. People in the ancient world did not have clocks to tell time nor did they wear watches.

One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. To measure time, ancient people used water flowing through a hole in a bowl and medieval people used sand moving through an hourglass.

One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. At night, people in early civilizations could measure time by the flow of sand or water but could not use a sundial.

One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. Quartz clocks are more precise than pendulum clocks yet atomic clocks surpass both in precision.

One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. Do you use a watch or cellphone to find out the time or do you rely on clocks wherever you go?

One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. Mechanical clocks first appeared in China around the twelfth century but did not show up in Europe until the fourteenth century.

One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. In the twelve-hour system, does 12:00 A.M. mean that it is noon, or that it is midnight?

One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. The twenty-four-hour system eliminates the confusion between A.M. and P.M., but few people outside the military use it.

One of the sentences in each item may be missing a comma to separate independent clauses or may contain an unnecessary comma. Remember that a comma is not needed between verbs when a single subject performs two actions. Select the answer option that eliminates the error or, if the original sentence is correct, select No change. In military time, 7:15 A.M. becomes 0715 so what does 7:15 P.M. become?