Who designed the first helicopter (直升飞机)? Who ___1___ the most famous pictures in the world? Who knew more about the human body than most ___2___? There is an answer ___3___ all thesequestions --- Leonardo de Vinci (达芬奇).
Leonardo may have been the greatest genius ___4___ have ever known. He lived in Italy around the year 1500, but many of his inventions seem modern to us today. For example, one of his notebooks has drawings of a helicopter. Of course, he couldn't ___5___ a helicopter with the things he had. But scientists say his idea would have worked.
But Leonardo ___6___ an inventor. He was one of the greatest artists of his day. By the time he was twenty years old, he was called a master painter, and as he got older he became ___7___ more famous. Sometimes he drew a hand ten different ways ___8___ he was ready to paint.
Many of Leonardo's wonderful paintings are still with ___9___ today. You may know one of his most famous works, the smiling woman ___10___ as the Mona Lisa.
（8）下列正确的是（ ）

A.before

B.after

C.because

D.when