简述无效问卷主要是指哪几种情况。

关于以上判决生效后各自的执行机关，以下描述正确的有哪些

A．康某、狄某和葛某应当由监狱执行

B．江某应当由少年犯管教所执行

C．封某应当由公安机关的看守所代为执行

D．尤某应当由公安机关执行

悬臂梁受力后在（）应力最大。

A.端部

B.中间

C.根部

D.靠端部3／4处

Weak dollar or no, $ 46,000-the price for a single year of undergraduate instruction amid the red brick of Harvard Yard-is (1) But nowadays cost is (2) barrier to entry at many of America’s best universities. Formidable financial-assistance policies have (3) fees or slashed them deeply for needy students. And last month Harvard announced a new plan designed to (4) the sticker-shock for undergraduates from middle and even upper-income families too.

Since then, other rich American universities have unveiled (5) initiatives. Yale, Harvard’s bitterest (6) , revealed its plans on January 14th. Students whose families make (7) than $60,000 a year will pay nothing at all. Families earning up to $ 200,000 a year will have to pay an average of 10% of their incomes. The university will (8) its financial- assistance budget by 43%, to over $ 80m.

Harvard will have a similar arrangement for families making up to $180,000. That makes the price of going to Harvard or Yale (9) to attending a state-run university for middle-and upper-income students. The universities will also not require any student to take out (10) to pay for their (11) , a policy introduced by Princeton in 2001 and by the University of Pennsylvania just after Harvard’s (12) . No applicant who gains admission, officials say, should feel (13) to go elsewhere because he or she can’t afford the fees.

None of that is quite as altruistic as it sounds. Harvard and Yale are, after all, now likely to lure more students away from previously (14) options, particularly state-run universities, (15) their already impressive admissions figures and reputations.

The schemes also provide a (16) for structuring university fees in which high prices for rich students help offset modest prices for poorer ones and families are less (17) on federal grants and government-backed loans.

Less wealthy private colleges whose fees are high will not be able to (18) Harvard or Yale easily. But America’s state-run universities, which have traditionally kept their fees low and stable, might well try a differentiated (19) scheme as they raise cash to compete academically with their private (20) . Indeed, the University of California system has already started to implement a sliding-fee scale.

7（）

A.less

B.more

C.richer

D.poorer

关于财产所有权的特征，下列表述正确的是( )。

A．财产所有权是相对的
B．它是一种最完全、充分的物权，它包含对所有物全面支配的权能
C．所有权的客体上可以同时并存两个或两个以上内容相同的所有权
D．所有人无权排除他人对于其财产违背其意志的干涉

比较长石砂岩和石英砂岩在成分和结构方面的差异.