问题
选择题
The element radium, ______ in the chemistry lab, gave off a blue light. [ ]
A. discovering
B. to be discovered
C. to discover
D. discovered
答案
答案：D
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The element radium, ______ in the chemistry lab, gave off a blue light. [ ]
A. discovering
B. to be discovered
C. to discover
D. discovered
答案：D