题干
The boy is ________ see the teacher because he ________ a mistake.
A：afraid of; has
B：afraid to; has made
C：afraid to; make
D：afraid of; made
答案(点此获取答案解析）
B
性是人类赖以生存和发展的物质基础，通常所指的生物多样性不包括（ ）