根据宪法规定内容，我国保密法又规定，公民或法人开办网站、论坛、博客以及上网等行为不得泄露、涉及和传播国家秘密事项。由此可见，保守国家机密是

①公民的一项基本权利               ②公民的一项基本义务

③公民的一项道德义务               ④公民的一项法定义务

A．①④

B．②③

C．①③

D．②④

With Halloween approaching, there exists a real concern among parents and teachers __________ trick or treating will become a seriously anti-social activity.

A．whether

B．what

C．that

D．how