关于膳食调查时间说法下确的是（）。A.至少应在春、秋进行两次以反映季节特点 B.每次

含有a mol FeBr₂的溶液中，通入x mol Cl₂。下列各项为通Cl₂过程中，溶液内发生反应的离子方程式，其中不正确的是（  ）

A．x＝0.4a，2Fe²⁺+Cl₂＝2Fe³⁺+2Cl^-

B．x＝0.6a，2Br^－+ Cl₂＝Br₂+2Cl^－

C．x=a，2Fe^2＋+2Br^－+2Cl₂＝Br₂+2Fe^3＋+4Cl^－

D．x=1.5a，2Fe^2＋+4Br^－+3Cl₂＝2Br₂+2Fe^3＋+6Cl^－

设x、y、z是空间不同的直线或不同的平面，且直线不在平面内，在下列几个条件中，能保证“若x⊥z且y⊥z，则x∥y”为真命题的有______．

①x为直线，y、z是平面； ②x、y、z均为平面；  ③x、y为直线，z为平面； ④x、y为平面，z为直线；⑤x、y、z均为直线．

我国新时期港口企业的重要文化特征之一，即为（）。

The following questions present a sentence, part of which or all of which is underlined. Beneath the sentence, you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.

These questions test correctness and effectiveness of expression. In choosing your answer, follow the requirements of standard written English; that is, pay attention to grammar, choice of words, and sentence construction. Choose the answer that produces the most effective sentence; this answer should be clear and exact, without awkwardness, ambiguity, redundancy, or grammatical error.

Because a rockslide had blocked much of the passage, the spelunking team was not able of exploring the till extent of the cave.（）

A. the spelunking team was not able of exploring the full extent of

B. the full extent was not able to be explored by the spelunking team of

C. the spelunking team was unable in exploring, to its full extent,

D. therefore the spelunking team was unable to explore the full extent of

E. the spelunking team was unable to explore the full extent of

某区环卫局为了加强本区的环境卫生工作。于2000年6月发布了一个决定，要求在该区内的居民住户每月向环卫局交纳卫生费50元，企业每月向环卫局交纳卫生费50元。区环卫局根据这项决定向某私营企业收取卫生费500元，该企业不服，向市环卫局申请复议。据此，下列说法错误的是______。

A．该企业可以对区环卫局发布的这项决定单位提起行政复议

B．该企业对区环卫局征收卫生费的行为既可直接申请复议，也可向人民法院起诉

C．该企业申请复议时，除以市环卫局为复议机关外，也可向区人民政府提请复议

D．若市环卫局先已依法受理该企业的复议申请，则在法定期阴内该企业不得向法院起诉