关于不定式的问题The 8% annual economic growth rate that officials believe is criticalto ensuring social stability.to 后面不是加动词原形吗?为啥这里是ing?难道不是不定式?还有这道题9．We laugh at jokes,but seldom ____D______ about how they work．　　A．we think         B．think we　　C．we do think        D．do we think又不是问句

关于不定式的问题The 8% annual economic growth rate that officials believe is critical
to ensuring social stability.to 后面不是加动词原形吗?为啥这里是ing?难道不是不定式?
还有这道题9．We laugh at jokes,but seldom ____D______ about how they work．
　　A．we think         B．think we
　　C．we do think        D．do we think
又不是问句