18.Seldom ____ him recently， for you see I’m preparing for the project.

A．I meet

B．do I meet

C．I have met

D．have I met

某果园有100棵橘子树，平均每一棵树结600个橘子．根据经验估计，每多种一颗树，平均每棵树就会少结5个橘子．设果园增种x棵橘子树，果园橘子总个数为y个，则果园里增种______棵橘子树，橘子总个数最多．