17. (A) The higher the speed, the greater the impact of collision, and so the death rate during speedingis very high. (B) The higher the speed, the greater the impact of collision, so that speeding causes accidents and very high deaths rate. (C) The impact of collision increases with speed, thus accounting for the high death rate in accidents due to speeding. (D) The impact of collision increases with speed, thus accounting for the high deaths rate during speeding accidents.

19. (A) Already in the Paleolithic Age, tens of thousands of years ago, the ancient Chinese knew how to make simple tools and ornaments from animal bones and tusks. (B) Already in the Paleolithic Age, millions of years ago, the ancient Chinese knew how to make simple tools and ornaments from animal bones and tusks. (C) By the Paleolithic Age, tens of thousands of years ago, the ancient Chinese were known how to make simple tools and ornaments from animal bones and tusks. (D) By the Paleolithic Age, millions of years ago, the ancient Chinese were known to have been making simple tools and ornaments from animal bones and tusks.

相關試題

相關試卷