Hoa sent aletter_____his cousin yesterday

C1: Hoa sent aletter_____his cousin yesterday.
A. from
B. with
C. at 
D. to
C2: He plans to vitsit Nha Trang next month
A. He must vitsit Nha Trang next month
B. He has to vitsit Nha Trang next month
C. He is going to vitsit  Nha Trang next month
D. He vitsit Nha Trang month