题目

下列语句中是命题的个数有( )①“垂直于同一条直线的两条直线必平行吗？”；②“一个数不是正数就是负数”；③“大角所对的边大于小角所对的边”；④“若x＋y为有理数，则x，y也都是有理数”；⑤“作△ABC∽△A′B′C′”．A. 2个 B. 3个 C. 4个 D. 5个 答案：【答案】B【解析】根据命题的基本概念，即可判定，得到答案.①疑问句：没有对垂直于同一条直线的两条直线是否平行作出判断，不是命题．②是假命题，0既不是正数也不是负数．③是假命题．没有指明在同一个三角形中．④是假命题．如x＝，y＝－.⑤祈使句．不是命题．所以②③④是命题．综上可13．Making friends is a skill．Like most skills，it（21）Bpatience．If you want to meet people and make friends，you must be willing to（22）Asome action．You must first go where there are people．You won't make friends staying home（23）C．    Joining a club or group，talking to those who like the same things （24）Ayou do is much easier．Or join someone（25）Bsome activity．    Many people are（26）Awhen talking to new people．（27）Dall，meeting strangers means seeing the unknown．And it's human nature to feel a bit（28）Cabout the unknown．Most of fears about（29）A new people come from doubts about（30）D．We imagine other people are（31）Cus--finding us too tall or too short，too this or too that． But don't forget that they must be feeling the same way．Try to accept yourself（32）Byou are，and try to put the other at ease．You'll both feel more comfortable．   Try to act self-confident even（33）Byou don't feel that way when you（34）Ca room full of strangers．Walk tall and straight，look at other people directly and（35）B．If you see someone you'd like to（36）A，say something．Don't wait for（37）Bperson to start a talk．   Just meeting someone（38）Cdoes not mean that you'll make friends with that person．（39）Bis based on mutual（相互的） likings and"give and take"．It takes time to（40）Afriendship．21．A．costsB．needsC．spendsD．wants22．A．takeB．makeC．doD．carry23．A．lonelyB．yourselfC．aloneD．with you24．A．asB．thatC．whichD．what25．A．withB．inC．onD．to26．A．shyB．excitedC．afraidD．worried27．A．AtB．ForC．InD．After28．A．unhappyB．usualC．upsetD．unlucky29．A．meetingB．talkingC．visitingD．speaking30．A．yourselfB．himselfC．yourselvesD．ourselves31．A．talkingB．sayingC．judgingD．laughing32．A．likeB．asC．whatD．that33．A．whenB．ifC．asD．what34．A．comeB．goC．enterD．step to35．A．laughB．smileC．cryD．jump36．A．speak toB．talk aboutC．say toD．call up37．A．otherB．the otherC．anotherD．others38．A．oldB．youngC．newD．little39．A．RelationB．FriendshipC．ConnectionD．Feeling40．A．developB．startC．keepD．change