大连理工大学考研复试什么时候开始？

下列关于X2分布的表述，正确的是

A.X2取值永远不会大于0
B.其均值等于其自由度
C.随着自由度的增大，X2分布趋于正偏态
D.多个标准正态分布变量的线性组合所得的新变量符合X2分布

1992 -26.患者咳嗽气喘，痰稀色白，形寒肢冷，舌淡苔白，脉迟，属于
A.风寒束肺 B.寒邪客肺 C.饮停于肺 D.痰湿阻肺 E.以上都不是

Text 1 Homework has never been terribly popular with students and even many parents,but in recently years it has been particularly scorned.School districts across the country,most recently Los Angeles Unified,are revising their thinking on this educational ritual.Unfortunately,L.A.Unified has produced an inflexible policy which mandates that with the exception of some advanced courses,homework may no longer count for more than 10%of a student's academic grade.This rule is meant to address the difficulty that students from impoverished or chaotic homes might have in completing their homework.But the policy is unclear and contradictory.Certainly,no homework should be assigned that students cannot complete on their own or that they cannot do without expensive equipment.But if the district is essentially giving a pass to students who do not do their homework because of complicated family lives,it is going riskily close to the implication that standards need to be lowered for poor children.District administrators say that homework will still be a part of schooling;teachers are allowed to assign as much of it as they want.But with homework counting for no more than 10%of their grades,students can easily skip half their homework and see very little difference on their report cards.Some students might do well on state tests without completing their homework,but what about the students who performed well on the tests and did their homework?It is quite possible that the homework helped.Yet rather than empowering teachers to find what works best for their students,the policy imposes a flat,acrosstheboard rule.At the same time,the policy addresses none of the truly thorny questions about homework.If the district finds homework to be unimportant to its students'academic achievement,it should move to reduce or eliminate the assignments,not make them count for almost nothing.Conversely,if homework matters,it should account for a significant portion of the grade.Meanwhile,this policy does nothing to ensure that the homework students receive is meaningful or appropriate to their age and the subject,or that teachers are not assigning more than they are willing to review and correct.The homework rules should be put on hold while the school board,which is responsible for setting educational policy,looks into the matter and conducts public hearings.It is not too late for L.A.Unified to do homework right.
It is implied in Paragraph 1 that nowadays homework_____

A.is receiving more criticism
B.is no longer an educational ritual
C.is not required for advanced courses
D.is gaining more preferences