题目内容：

英语-主谓一致,
1>.One third of the students in our class are/is girls.
2>.Seventy percent of the surface of the earth are/is covered with/by water.
3>.Half of the project has/have been
completed in the past two months.
4>.Some students are studying in the
classroom,while the rest are/is
enjoying the performances.

优质解答

are  几分之几的单复数看的是后面的名词,这里的名词是students,所以算复数.

is 百分之几同样看后面的名词,这里的名词是surface,算单数.

has,单复数看the project,算单数.

are 单复数看the rest所指的名词,这里所指的是students,算复数.