B. to say
"It's very kind of you to say." (After "kind of you," we use the infinitive form.)

B. to do
"Please show me how to do this." (The phrase "show me how to" is followed by the infinitive form.)

D. to learn
"One is never too old to learn." (The phrase "too old to" is followed by the infinitive form.)

C. to go
"You are old enough to go out alone." (The phrase "old enough to" is followed by the infinitive form.)

A. to meet
"I'm very glad to meet you." (After "glad," we use the infinitive form.)

B. to know
"It's nice to know you." (After "nice," we use the infinitive form.)

B. to see
"You have no right to see my daughter." (The phrase "no right to" is followed by the infinitive form.)

B. doing
"Please tell me what you are doing." (After "tell me what," we use the gerund form.)

A. to read
"I forbid you to read my letter." (The verb "forbid" is followed by the infinitive form.)

A. say
"We stopped to say hello to her." (After "stop," when referring to the purpose of the action, we use the infinitive form.)

B. to help
"We came to help her." (After "came," we use the infinitive form to express purpose.)

C. to teach
"I'll invite her to teach my daughter." (After "invite," we use the infinitive form.)

C. to go
"I don't feel like going to the cinema now." (After "feel like," we use the gerund form.)