Question

Fill in the blank with the most appropriate word.
His father told him ____ careful.

• A. being
• B. to be
• C. be
• D. been

Answer 1

The correct option is B to be

In English reporting verbs like tell/told etc. are often followed by an object and then an infinitive with ‘to’. So, as in this context the reporting verb "told" is followed by the infinitive "to be". In this case the 'to' infinitive indicates the purpose of an action. Thus, option B "to be" is the correct answer.
"Being" is the present participle of the verb "be". However, in this context the infinitive is required after the object. Hence Option A is incorrect.
The verb ''be'' by itself (without the infinitive) in incorrect. Hence option C is incorrect.
''Been'' is the past participle of the verb ''be' and some students may think it is appropriate to use with the past participle verb ''told''. However, as the verb 'told' is a reporting verb it is used with an infinitive. Hence option D is incorrect.