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【单选题】
利用大棚栽培农作物时，科技人员常棚内施放适量的C02．其作用是（ ）A.
C02：会使大棚内的温度升高
B.
CO 2 ：可促进植物进行光合作用
C.
C02：能灭火，可避免火灾的发生
D.
CO2．可使害虫窒息死亡，防治植物病虫害
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【单选题】直线y=kx+1（k∈R）与椭圆 x 2 5 + y 2 m =1 恒有公共点，则m的取值范围是（ ）
A.
[1，5）∪（5，+∞）
B.
（0，5）
C.
[1，+∞）
D.
（1，5）
【多选题】HPLC的特点包括()
A.
Widely available
B.
Relatively easy to use
C.
High accuracy and precision
D.
Extended ytical time
E.
Relatively high cost
【简答题】( ) as the term we all familiar with, is a relatively large, low-cost, low-margin, high-volume, self-service operation designed to serve the consumer’s total needs for grocery and household products.
【单选题】One of the reasons for the relatively high price of many drugs is the huge cost of ____and development.
A.
experiments
B.
research
C.
trials
【简答题】In electronicpower supplies there is often a need to isolate the output from the input andreduce the weight and cost of the unit. In other applications, such as inaircraft, there is a strong incentive...
【单选题】Which of the following are primary concerns of the bank manager?
A.
maintaining sufficient reserves to minimize the cost to the bank of deposit outflows
B.
extending loans to borrowers who will pay low interest rates, but who are poor credit risks
C.
acquiring funds at a relatively high cost, so that profitable lending opportunities can be realized
D.
maintaining high levels of capital and thus maximizing the returns to the owners
【单选题】不论k为何值，直线y=kx+1与椭圆 x 2 7 + y 2 m =1有公共点，则实数m的范围是（ ）
A.
（0，1）
B.
[1，+∞）
C.
[1，7）∪（7，+∞）
D.
（0，7）
相关题目：
【单选题】直线y=kx+1（k∈R）与椭圆 x 2 5 + y 2 m =1 恒有公共点，则m的取值范围是（ ）
A.
[1，5）∪（5，+∞）
B.
（0，5）
C.
[1，+∞）
D.
（1，5）
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