三棱锥D﹣ABC中，AC=BD，且AC⊥BD，E，F分别分别是棱DC，AB的中点，则EF和AC所成的角等于（　　）

背景材料：2017年广东两会上，省委书记胡春华再次提出要振兴粤东西北，补齐广东的短板，率先实现全面小康社会，早日实现共同富裕的目标。9年级1班的同学看到了这样的新闻之后，也相应搜集了一些有关振兴粤东西北的素材，请你一起参与探究。

一个质量为45kg的同学所受的重力是多大？（g=10N/kg）

根据课文和首字母填空。
    Sandy and Sue are in a shop. They want to buy two p____ of sweets，but they are one shilling e____. That's all their p____ money. At last, they buy two small lollipops i____.
    In the afternoon, Sandy and Sue come back home from school. Tea's r____. Sandy and Sue are very h____, but Sandy's hands are very d____. Mother asks Sandy to go and w____ his hands at o____. Now Sandy's hands are clean. Look at Mum's nice clean t____! Sandy cleans his hands with it.
    On Sunday, Sue and Mum are going shopping. Mum sees a pair of nice s____, so she wants Sue to t____ them on. They are very t____ for Sue. Sue wants the pink ones and she thinks they're very p____. They're j____ right.

最近的一份调查显示，在中国，许多英语学习者都想学好英语，但是他们之所以学不好英语是因为许多英语学习者并不关心英语学习过程本身，他们只是把学习英语当作一种责任，并不是真正对学习英语感兴趣。只有重视英语学习的过程，把学习英语当作自己的爱好，才能真正学好英语。
请根据上面的材料，用英语写一篇80词左右的短文。
注意：1. 要点完整、层次清楚、语法正确、上下文连贯。
2．不要逐句翻译上面所提供的信息材料。
提示：关心：care about      学习过程：learning process      责任：duty
All English learners would like to learn English well.________________________________