A:Because he was at home every day.
B:Because he played the violin every day.
C:Because he did homework every day.
下列哪一项不利于生物多样性的保护( )
(2015•海南)近年来,我国服务贸易的进出口总值占商品进出口总值的十分之一左右,且在加入世界贸易组织的十余年中一直处于逆差状态。这种状况长期存在的主要原因是( )