Fill in the necessary modal verbs can\ can`t , may\may not , must\mustn`t , to have to in the correct form  1) .......... you swim well ?- Oh ,no.I........ swim very well .2) Ben ,you ........be polite with your sister !3) ....... I come in ? -No, you..........You are late. 4)Boys ,you ..........talk in class. 5) Helen ........work hard , because she wants to pass her exam.