A number of the students have come here already.怎么译

选择：A number of students _____ come a number of the students a number of students还是a number of the students Only a small number of students come from the city.这句话中come怎 A number of students,请问 A number of 与the number of students有 a small number of students ( ) the subway The number of students 英语.Some of the students have already learned enough English Some of the students have already learned enough English to_ Some of the students have already learned enough English to We have students---all over the world here A from B COme fro (The) number of the college students who(have )mobile phones