二力杆受力方向的判断

the old woman couldn't help ____tears when she heard the sad news.A to burst into B burst out 边长为4的正方形ABCD中,点O是对角线AC的中点,P是对角线AC上一动点.过点P作PF⊥CD于点F……急求高手解答作PE⊥PB交直线CD于点E,设PA=X S△PCE=Y（1）求证：DG=EF（2）当点P在线段AO上时,求Y关于X的函 边长为4的正方形ABCD中,点O是对角线AC的中点.P是对角线AC上的一点,过点P作PF垂直CD于点F,作PE垂直于PB交直线CD于点E,设PA=X,S三角形PCE=Y,(2) 当点P在线段AO上时,求y关于x的函数关系式及自变量x的取 只能接不定式的动词有哪些 中外名胜古迹$$$$$$$$$$$$ 什么情况下接动词不定式?比如一般recall、remember、forget后面都接doing sth,请问这些怎么区别,为啥它后面就接doing sth.recall、remember、forget这三个单词有特殊的什么含义么? 所有的动词都接不定式吗?To err is human,to forgive divine.It always pays to tell the truth.It's been a pleasure to be able to help you.The important thing is to save lives.这些英语句子中的err pay pleasure 都必须接带to 的不定 be scared of可以用什么代替 描写人态度镇定的词语 天气恶劣的词语?态度镇定的词语?多多的 写出描写态度镇定的词语 但英语政治不行,我想考个二本我现在考490多分,我该怎么办呢? 求数学小数、整数的四则混合运算,不要分数.要100道. 木兰回到家乡后喜悦心情的诗句是? make fun of 的同义词 单词分类(接不定式还是...)将下列单词分类(就这一题)mind want make let keep hope start like plan practise help fail enjoy finish接不定式(to do):省to不定式(do):接动名词(doing) 哪些单词后只能接动词不定式,而那些单词只能接doing Be unaware of 的同义词 be aware of的同义词 be unaware of sth可以换成什么/be aware of sth 呢- -是be know of sth 和be don't know of sth 吗？ 紧张的做各种事情是哪个词语的解释? 一道高一数学必修4的题cos20*cos40*cos80= 红楼梦开头诗是什么意思 He always goes to work______A all the time B in time C on time 竟然属于什么词性 Fother always goes to work quickly in the morning.=Father always goes to work__ __ __in the morning I always go to work in the morning.What about father?He always goes to work in the morning,too为例I am going to stay at school this afternoon.What about Sue?__________________I can play hopscotch.What about Liz and Lillie?__________________ love to the depths of the people,we have a humble heart.这句话怎么翻译 people usually have 15days off.译一下off. 燕子飞翔的抒情,说明和描写.（每部分200字左右,说明只需80字） He always drives to work.句型转换He always goes to work_______ _____. “当前、现在、马上”分别是什么词性