题干

如图是一农田长期使用一种农药后害虫群体密度变化曲线.不符合达尔文进化观点的是(  )

A:从曲线变化可知,害虫群体中原来就存在抗药性个体

B:随着农药的使用,害虫群体的抗药性逐渐增强

C:农药的使用使害虫发生了定向变异

D:害虫抗药性的形成是农药对害虫定向选择的结果

上一题 下一题 0.0难度 选择题 更新时间:2015-03-25 06:16:34

答案(点此获取答案解析)

C

同类题5

阅读下面短文,掌握其大意,然后从1~15各题所给的A、B、C和D项中,选出最佳选项。

People often say that you can not change the environment, but can change yourself; you can not change the past, but now can be changed; you can not change the facts, but can change attitudes.

Indeed, one key to the success lies in his 1. The difference between successful people and the losers are: 2attribute setbacks and difficulties to personal ability, experience, imperfect, to 3the internal(内在的), they are willing to continuously improve and develop the right direction; while the losers will blame on the opportunity, and the environment injustice, emphasizing external(外在的) and4factors that created the position of their life, they always5, wait and give up!

Person’s appearance or his family is a priori (先验的)condition that can not be changed, but at least the inner state, the spirit of the will is 6 in their control. Mentality determines the final height of life. There is no absolute bad thing, only the absolute7mentality. If a person even cannot 8the state of mind, how can he deal with things more complicated than the mentality?

No matter what the situation is, a person’s 9 is very important. That you put10or numbness in your work makes completely different. Emerson said:When one keeps moving toward his goal,the whole world will stand away from his way.On the contrary, failure is not because we do not have the11, but because we are susceptible(易受影响的) to all around us with an unstable attitude, and are easily12

As long as we believe the power of mind, change our attitude and have the13to face the disappointments in life, do not despair, we can14succeed. Believe the power of mind because 15determines the final height of life.