一枝钢笔能换3枝圆珠笔,4枝圆珠笔能换7枝铅笔,那么4枝钢笔能换多少枝铅笔?
21枝
—Is there a ______ near here? I want to buy a football.
—Oh, yes! It’s next to the bookshop.
A.sports shop
B.flower shop
C.shoe shop
D.stationery shop
伞菌目的子实层生于()的两面,其内部的组织称为(),子实层主要由()组成,有的种类在子实层中还有少数的()。