问题
选择题
It is these poisonous products_____can cause the symptoms of the flu , such as headache and aching muscles .
A．who
B．that
C．how
D．what
答案
答案：B
句意：正是这些有毒物质能够产生流感征兆，如头疼、肌肉疼痛等。该题考查强调句型，强调主语。把it is…that 去掉后，句子仍然完整。
