19世纪三大科学发现是：细胞学说、进化论、能量守恒定律。[ ]
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下列各种动物中，哪种动物是病原体？（ ）
A．蛔虫
B．虱子
C．跳蚤
D．鼠
连词成句。
1. basketball, morning, played, Sunday, they, on
2. do, he, weekend, did, on, what, the
3. studied, she, math, the, last weekend, for, test
4. visited, grandmother, my, last, I, Sunday
5. party, had, Mary, Saturday, last, a, dinner
