People start to question some nutrients effect probably because______.
A. the experiments on mice have failed
B. they may affect brain development
C. mothers" diet can influence children
D. they may disrupt normal biological mechanisms
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The author believes that it is important that spoken language______.
A. be learned at an early age
B. not be confused with body language
C. not be confused with written language
D. be learned in the context of a caring relationship
《国际民用航空条约》规定各缔约国可在其领空行使哪些主权？
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