下列实验操作及其先后顺序均正确的是（　　）

    Here are six steps to better studying.

Pay attention in class

    Do you have trouble paying attention in class? Are you sitting next to a loud person? Tell your teacher or parents about any problem that is preventing you from paying attention.

Take good notes

    Write down facts that your teacher mentions or writes on the board. Try to use good handwriting so you can read your notes later. It's a good idea to keep your notes organized by subject.

Plan ahead for tests and projects

    Waiting until Thursday night to study for Friday's test will make it hard to do your best. One of the best ways to make sure that doesn't happen is to plan ahead. Write down your test dates. You can then plan how much to do after school each day, and how much time to spend on each topic.

Break it up

    When there's a lot to study, it can help to break things into several parts. Let's say you have a spelling test on 20 words. Instead of thinking about all of the words at once, try breaking them down into five-word groups and work on one or two different groups each night.

Ask for help

    You can't study effectively if you don't understand the material. Be sure to ask your teacher for help. If you're at home when the confusion occurs, your mom or dad might be able to help.

Sleep tight

    So the test is tomorrow and you've followed your study plan—but suddenly you can't remember anything! Don't panic. Your brain needs time to digest all the information you've given it. Try to get a good night's sleep and you'll be surprised by what comes back to you in the morning.

人的性别是由受精卵中性染色体的组成决定的．男性的性染色体组成是____ ，女性的性染色体组成是____ ．

阅读下面的文言文，完成后面题目。

    李焘字仁甫，眉州人。绍兴八年，擢进士第。知双流县。仕族张氏子居丧而争产，焘曰：“若忍坠先训乎?盍归思之。”三日复来，迄悔艾无讼。又有不白其母而鬻产者，焘置之理，豪强敛迹。

    知荣州。夏秋率苦水潦，焘筑防捍之。除潼川府路转运判官，入境，劾守令不职者四人。县多聚敛，焘括一路财赋额，通有无，酌三年中数，定为科约，上之朝，颁之州县。

    除直显谟阁、湖北转运副使，总饷吕游问入奏，焘摄其事。岁饥，发鄂州大军仓振之，僚属争执不可，焘曰：“吾自任，不以累诸君。”寻如数偿之。游问返，果劾焘专。上止令具析，不之罪也。

    八年，直宝文阁，帅潼川兼知泸州，首葺石门堡以扼夷人，奏乞戒茶马司市叙州羁縻马毋溢额，戒官民毋于夷、汉禁山伐木造舟，奏移锁水于开边旧池，皆报可。

    政和末，澧、辰、沅、靖四州置营田，募人开边，范世雄等附会扰民，建炎罢之。乾道间，有建请复置者焘为转运使尝奏不当复已而提刑尹机迫郡县行之田不能给。焘至是又申言之，请度田立额，且约帅臣张栻列奏，诏从之。境多茶园，异时禁切商贾，率至交兵，焘曰：“官捕茶贼，岂禁茶商?”听其自如，讫无警。

    淳熙十一年春，乞致仕，优诏不允。上数问其疾增损，给事中宇文价传上旨，焘曰：“臣子恋阙，非老病，忍乞骸骨。”因叩价时事，勉以忠荩。又闻四川乞减酒课额，犹手札赞庙堂行之。

    病革，除敷文阁学士，致仕。命下，喜曰：“事了矣。”口占遗表云：“臣年七十，死不为夭，所恨报国缺然。愿陛下经远以太祖为师，用人以昭陵①为则。”辞气舒徐，乃卒，年七十。谥文简，累赠太师、温国公。

（选自《宋史•李焘传》，有删改）

【注】①昭陵：唐朝皇帝唐太宗李世民与文德皇后长孙氏的合葬陵墓，这里代指唐太宗。