WTO《技术性贸易壁垒协定》要求各成员国应以国际标准或其相应部分作为制定本国技术法规的基础。
参考答案：对
免疫功能主要是____________、___________和_____________。
Teachers recommend parents ____ their children under 12 to ride bicycles to school for safety.[ ]
A. not allow
B. do not allow
C. mustn't allow
D. can't allow
