题干
He is clever, but not ______.
A：hard-working
B：work hard
C：hard work
D：working hard
答案(点此获取答案解析）
A
He is clever, but not ______.
A：hard-working
B：work hard
C：hard work
D：working hard
人类在保护这一濒危物种过程中取得的重大技术突破，具有里程碑意义。从联系的观点看，人工繁殖中华鲟的成功说明