显示所有男生的信息，不正确的命令是？ A: db.students.find({"sex":"男"}) B: db.students.find("this.sex=='男' ") C: db.students.find({"this.sex='男' "}) D: db.students.find({$where:"this.sex=='男' "})

查询专业不存在的学生信息，正确的命令是？ A: db.students.find({"major":null}) B: db.students.find({"major":{$in:[null],$exists:true}}) C: db.students.find({"major":{$exists:false}}) D: db.students.find({"major":{$exists:true}})

Students find out sentences that show the ______ of the Great Wall

Students can find reports on any virtual topic in the ______.

________ students often find it difficult to live in China at first.

Art class is where students come to find their____________.

查询天心区的男学生的信息，正确的命令是？ A: db.students.find({"address":"天心区"},{"sex":"男"}) B: db.students.find({"address":"天心区","sex":"男"}) C: db.students.find({$and:{"address":"天心区","sex":"男"}}) D: db.students.find({$and:[{"address":"天心区"},{"sex":"男"}]})

AYES is not going to help students find jobs in the automobile industry.

Why do some students find it easy to balance schoolwork and socializing?

The author conducted a survey among undergraduate students trying to find out __________.