Valentine’s Day was the time my father chose to show his love for the special people in his life. Over the years I fondly thought (31) him as my "Valentine man".

My first recollection of the magic he could bring to Valentine’s Day came when I was six. That morning at the breakfast table I found a card and a gift-wrapped package at my chair. The card was (32) "Love, Dad" and the gift was a ring with a small piece of red glass to represent my birthstone, a ruby.There is (33) difference between red glass and rubies to a child of six, and I remember wearing that ring with pride that all the cards in the world (34) not surpass.

As I grew older, the gifts gave (35) to heart-shaped boxes filled with my favorite chocolate and always included a (36) card signed "Love,Dad". In those years my thank-you became more of a perfunctory response. The cards seemed less (37) , and I took for granted that the Valentine would always be there. I had (38) my hopes and dreams in receiving cards and gifts from "significant others" and "Love, Dad" just didn’t seem quite enough.His final card remains on my desk today. It’s a (39) of how special fathers ean be and how important it has been to me over the years to know that I had a father who continued a tradition of love with simple acts of understanding and an ability to express happiness over the people in his life.Those things never (40) , nor does the memory of a man who never tried being my Valentine.

34（）。

A. could

B. did

C. must

D. should

按照土中单个颗粒的粒径大小和组成，将土分为哪几种？