10. How can you change a simple tense to perfect tense in a sentence?
A. by using helping verb has/have/had + past participle of the verb
B. by using will be or shall be + verb -ing
C. by using am, is or are + verb -ing
D. by using was or were + verb-ing
11. How can we identify if the sentence is using simple or perfect tense?
A. there is no difference at all
B. never mind, it's not important
C. we cannot identify the tenses used
D. by analyzing on the tense of the verb being used in the sentence