实验室常用的洗涤剂有（）。
A.铬酸洗涤液
B.酸性草酸
C.硝酸溶液
D.碱性溶液
参考答案：A, B, C, D
Martin Cooper , a US researcher , was considered _______ the first cell phone .
A．invented
B．to invent
C．having invented
D．to have invented
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