The main idea of the second paragraph is______.
A．diversity of the workforce has its disadvantages
B．besides new opportunities, the changing workforce also contain challenges
C．the low educational levels of immigrants is a challenging problem
D．America had better face the problem of declining skills or it will suffer

未分类题The invention of the method of altering childrens behavior. is owing to______.A．the desirable behaviorB．reinforced practiceC．decades of studyD．replacement of unwanted behaviors

未分类题Which of the following is NOT one of the factors affecting the result of changing childrens behavior?A．The reinforced practice of the positive opposite.B．The way parents behave at home.C．The influences of other relationships of children.D．The separation of the parents of young children.

未分类题According to the author, the entertainment he discusses was so popular because______.A．people didn't know they were being trickedB．people liked the performances and the chance to test their own judgmentC．people had a double consciousness of love and hate of itD．people merely treated it an interesting game of deciding which was real and not

未分类题It can be concluded from the text that______.A．the entertainment died out as society became more skepticalB．the skills the entertainment employed were part of its ultimate demiseC．the entertainment used highly skilled understanding of human natureD．the entertainment served a very important part role in the lives of people

未分类题By mentioning microbe, the author intends to______.A．advocate that animals with a nervous system can all learnB．argue that learning is an adaptation to a changing environmentC．claim that learning has some kind of side effectsD．prove that the adaptation may not include learning with a nervous system