5. Three years ago Mark __ speak a word of French. a. can't b. won't be c. wasn't able to able to 6. When the scientist __ his talk on space tourism he'll answer your questions. a. finishes b. will finish c. is going to finish

Here are the answers and explanations:**5. Three years ago Mark __ speak a word of French.*** **The correct answer is (c) wasn't able to.** * This sentence describes a past inability. "Wasn't able to" is the correct past tense form to express this.**6. When the scientist __ his talk on space tourism he'll answer your questions.*** **The correct answer is (a) finishes.** * This sentence uses a future tense ("he'll answer") and a time clause ("when the scientist..."). The time clause uses the present tense ("finishes") to indicate an action that will happen before the action in the main clause.