Verbs. Tenses. Present Simple; Present Continuous; Present Perfect; Present Perfect Continuous.

a). have spent;

b). are spending;

c). spend.

a). walks...waits;

b).walks ... is waiting;

c). is walking..... waits.

a). does she;

b). doesn't she;

c). does Ann.

a). does help;

b). helps;

c). do help.

a). is opening;

b). does open;

c). opens.

a). is having;

b). has got;

c). have got.

a). do not understand;

b). am not understanding;

c). not understand.

a). does not rain;

b). isn't rain;

c).isn't raining.

a). have come ... live;

b). am doing...am living;

c). come...am living.

a). have known;

b). have been knowing;

c).know.

a). have always been buying;

b).always buy;

c). are always buying.

a). is your sister liking;

b). does your sister like;

c). has your sister liked.

a). is studying;

b). has been studying;

c). studies.

a). have you usually had;

b). do you usually have;

c). are you usually having.

a). has just come;

b).just came;

c). is just coming.