Members of the media _____to cover Royal events or stories should make themselves familiar with the guidance provided in this section.

A．seek

B．sought

C．seeking

D．to seek

（）是种子发生混杂的主要原因。

A、机械混杂和生物学混杂

B、生物学混杂和动物学混杂

C、植物学混杂和机械混杂

D、生物学混杂和植物学混杂