A. My friend suggested that I should improve my social skills.

B. My friend suggested I improving my social skills.

C. My friend suggested I improves my social skills.

D. My friend suggest I should improve my social skills.

A. Although he was tired, he had to finish his homework.

B. Although he is tired, he have to finish the homework.

C. Although he was not tired, he has finish his homework.

D. Although he tired, he has to finish the homework.