He sent me a letter.

She found a forget-me-not and remembered her old lover.

He is good at expressing his opinions skillfully.

He repeated my words, acting as if they were his own opinion.

He is good at skillfully expressing his own opinions.

One part is important.

He is a second-year high school student.

It is important for each person to fulfill their role.

He acted according to my instructions one by one.

He is carefully doing each and every task.