Question 15: Scientists have (A) tried to assess (B) the impact of (C) human activities on the environmental(D).
Question 16: If (A)I passed (B) this exam, I’ll go (C) to the (D) university next summer.
Question 17: All (A) new workers mustn’t (B) have a (C) medical examination(D).
Question 18: Do you remember (A) a (B) name of the hotel which (C) is at (D) the end of this street?