ifthelaunchissuccessfulin2005,chinawillbethethirdcountry（tosend）theastronautsintospaceaftertheusaandRussia.括号为什么要用tosend?用sending

Question

if the launch is successful in 2005,china will be the third country （to send） the astronauts into space after the usa and Russia.
括号为什么要用 to send?用sending

Answer 1

这是一个习惯用法.即：当被修饰词前面被序数词/形容词最高级或the last/only等修饰时,如果其后再用动词来做后置定语的话,则必须使用动词不定式形式.再如：He was the first runner to pass the finishing line.他是...