$1$. cry ( S + used to + V )
$2$. to open ( Tường thuật gián tiếp )
$3$. let ( S + should + V )
$4$. playing ( like + V-ing )
$5$. has he learnt/ has learnt
$6$. has learnt/ was
$7$. haven't eaten ( QKTD )
$8$. did you see/ saw
$9$. hasn't written ( QKTD )
$10$. to send ( S + want + N )