如图是我国玉米主产区分布示意图．读图回答下列各题．

根据短文内容，完成下面各题，每空词数不限 
My English teacher is Mary. She is from England. Her father is Nick and her mother is Rose. They are very old. So they don’t work now. Mary has two children, a son and a daughter. Her daughter is Betty. Her son is John. Mary and her daughter are in China, but her husband Paul Smith is in England. Her son is in America. Paul is a police officer. John is a college student. Betty and I are in the same school. We are classmates. We are in Class Three, Grade Seven.
Betty is Mary’s____ .
Betty’s father is a ____  (职业).
____ teaches the writer(作者) English.
Mary comes from ____  .
Nick and Rose are Mary’s ____  .

如图所示，质量为M的木板放在水平桌面上，一个质量为m的物块置于木板上．木板与物块间、木板与桌面间的动摩擦因数均为μ．现用一水平恒力F向右拉木板，使木板和物块体共同向右做匀加速直线运动，物块与木板保持相对静止．已知重力加速度为g．下列说法正确的是（   ）

对实验现象的观察和分析，有助于获得化学知识并学会科学探究的方法．下列对实验现象的分析合理的是（　　）