Studentsshoulddoeverythingtheycan__theirstudy.A.improveB.toimproveC.improvingD.improved
不太明白.别人给我讲说,如hedidwhathecantohelpthepoor(他尽其所能帮助穷人,whathecan宾语从句,后面的todo是目的状语.请问can后面的动词do呢?