Since William had been seriously ill for several months, his parents were worried about()to return to school full-time.
A. he wanted
B. he wanting
C. him to want
D. his wanting
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一个人的语言能力主要包括有关自己母语的语音、()、语法的知识,以及文字方面的知识。
Thomas Becket spent()years on the continent and returned to England in 1170.
A. four
B. five
C. six
D. seve
在较寒冷的条件下,用加热器加热天然气,给气流管线保温,()抑制天然气水合物的生成。
A. 可以
B. 不可以
C. 在短暂时间内能
D. 也许能
根据系统安全工程的观点,危险是指系统中存在发生不期望后果的可能性超过了人们的()。
A. 承受程度
B. 认知能力
C. 实践水平