①函数f(x)=[x)﹣x的值域是(0,1]
②若{an}是等差数列,则{[an)}也是等差数列
③若{an}是等比数列,则{[an)}也是等比数列
④若x∈(1,2017),则方程[x)﹣x=sin π2 x有1007个根.
A:②
B:③④
C:①
D:①④
走进美丽的校园,坐在明亮的教室,见到新老师和新同学,我们每个人都会产生这样或那样的想法。下面是一些同学的想法,你赞同的是( )
Most people have jobs. They go to 1 nearly every day. Some people are lucky. Either they have very interesting jobs or they earn a lot of 2. Most people are not so lucky. Either their jobs are a bit 3 or they don't get well 4.
The most interesting jobs are often the most 5. People spend long time learning how to do them. Doctors study for 6 six years after finishing school. Airline pilots(飞行员) study longer. They have to learn to fly small airy craft first, and then 7 move up to bigger and bigger aircraft. Most airline pilots are at least 30 years old.
Some 8 people have interesting and well-paid jobs. Many successful athletes(运动员) are usually under 35. Older people usually can't 9 these sports very well because they can't move fast enough.
Most people work until they are 60 or 65 year old. Some people 10 retire. These people usually have very interesting jobs. Writers, artists, musicians and actors usually work until they die.
如图显示了第二次世界大战后美国对欧洲国家经济援助状况。这一状况反映了( )
下列关于种子的说法,不正确的是( )