搜题请搜索小程序“爱下问搜题”
问题 解答题
解方程：
（1）
x-1
4
-1=
2x+1
6
            
（2）
x-1
0.2
-
x+1
0.5
=2．
答案

（1）去分母得：3（x-1）-12=2（2x+1），

去括号得：3x-3-12=4x+2，

移项合并得：-x=17，

解得：x=-17；

（2）方程变形得：5（x-1）-2（x+1）=2，

去括号得：5x-5-2x-2=2，

移项合并得：3x=9，

解得：x=3．

选择题

全球性大气污染主要表现在（  ）

A.酸雨、温室效应 、生物入侵

B.温室效应、含铅废气、酸雨

C.温室效应、乱砍滥伐、臭氧层破坏

C.酸雨、温室效应、臭氧层破坏
查看答案
单项选择题

I got a job teaching special education at a school in Coachella, California, a desert town about 170 miles from home. It was no (1) job. Street gangs (2) around the school after dark."Be careful," Dad warned me during one of my frequent weekend (3) home. He was concerned about my living (4) , but I needed to be on my own.One evening, I stayed after school to rearrange my classroom. (5) , I turned out the light and closed the door. Then I (6) toward the gate. It was (7) ! I looked around. Everyone had gone home.After (8) all the exits, I found just enough (9) to squeeze under a gate in the back of the school. Then I walked toward my car, parked in a field behind the building.Suddenly I heard voices. I (10) around and saw at least eight boys following me. (11) my pace, I reached into my shoulder bag to get my key. I (12) all over the inside of my handbag. But the key wasn’t (13) ! Dear Lord, please help me, I prayed (14) . Suddenly, my fingers touched a loose key in my purse. I didn’t even know if it was for my car, but I took it out and (15) it. It worked!I opened the door, slid in and locked it—just (16) the teenagers surrounded the car. Trembling , I started the engine and (17) away. When I returned to my apartment, the phone was ringing. It was my Dad. I didn’t tell him about my experience; I didn’t want to (18) him. "Oh, I forgot to tell you!" He said, "I had a(n) (19) car key made and slipped it into your purse—just (20) you ever need it.

第（20）空应选择（）

A．even if

B．on condition that

C．in case

D．in time
查看答案