He answered my questions... because he didn't look at my eyes and seemed to be very servous.(honest)

1, He answered my questions... because he didn't look at my eyes and seemed to be very servous.(honest)
2, English is a...subject at schools in VN.(compel)
3, The mother has to...the milk because it's cold.(hot)
4, Put the...into the pan and cook it for about half ann hour.(mix)