protect+sb+from什么意思

蔚汤鸣4143It's+adj. for sb. to do sth.这个句型什么意思? -
洪忽弦13848765365 ______ It's+adj. for sb. to do sth.:做某事对于某人来说是… 【例1】It's necessary for us to have healthy eating habits. 拥有健康的饮食习惯对于我们来说是必要的. 【例2】It's important for us to protect the environment. 保护环境对zhidao于我们来说是重...

蔚汤鸣4143F(s)=1/[s*(s+1)^2]的拉氏反变换 -
洪忽弦13848765365 ______ 设原式=a/s+b/(s+1)+c/(s+1)² 将右边通分,分子为a(s+1)²+bs(s+1)+cs =(a+b)s²+(2a+b+c)s+a 比较系数可知a=1,a+b=0,2a+b+c=0 解得a=1,b=-1,c=-1 原式=2/s-1/(s+1)-1/(s+1)² 自己查表找反变换

蔚汤鸣4143下面程序的输出是 main() { char s[ ]=＂121＂; int k=0, a=0, b=0;...
洪忽弦13848765365 ______[答案] You must be one of the most dilligent students in your class.It's important for us to protect wild animalsMary started early so that she could catch the first bus to school.I have two brothers.One...

蔚汤鸣4143一种化学方程式的配法,令每个化学式前的系数为字母a、b、c.然后根据原子守恒解得各系数以这个方程式为例:KMnO4 + K2SO4 +H2SO4——K2SO4 +... -
洪忽弦13848765365 ______[答案] 太麻烦了! a+2b=2d(K).(1) a=e(Mn).(2). 4a+4b+4c=4d+4e+f(O).(3) b+c=d+e(S).(4) 2c=2f(H).(5) 联立几个式子. (但是亲爱的楼主,你没有发现方程式左右两边都有K2SO4吗?) 如果是H2SO3的话: 那根据氧化还原反应: Mn由+7降为+2降低5价 S...

蔚汤鸣4143题目是这样的:在三角形ABC中,已知三内角满足2A=B+C,边BC=2倍的根号3,设内角B=x,周长为y.(1)求函数y=f(x)的解析式和定义域;(2)求y的最大... -
洪忽弦13848765365 ______[答案] (1)3A=A+B+C=π,A=π/3,B=x,C=2π/3-x x∈(0,2π/3) a/sinA=b/sinB=c/sinC 而a=2√3,sinA=√3/2 则b=4sinx,c=4sin(2π/3-x) y=f(x)=a+b+c=2√3+4sinx+4sin(2π/3-x) =2√3+8sin(π/3)cos(x-π/3) =2√3+4√3cos(x-π/3) x∈(0,2π/3) (2)ymax=6√3 当且仅当cos(x-π...

蔚汤鸣4143怎么用主语+COST+SB+钱造句 -
洪忽弦13848765365 ______ it cost me 300 yuan to buy it

蔚汤鸣4143如图 求∠A+∠B+∠C+∠D+∠E+∠F的值【快 -
洪忽弦13848765365 ______ ∠A+∠B+∠C+∠D+∠E+∠F+∠G+∠H+∠S=180°*3 ∠G+∠H+∠S=180° ∴∠A+∠B+∠C+∠D+∠E+∠F=180°*2=360°

蔚汤鸣4143s三角形abc等于二分之一半径(a+b+c) -
洪忽弦13848765365 ______[答案] 证明:设O为ΔABC的内心, 过O作OD⊥AB于D,OE⊥BC于E,OF⊥AC于F, 则OD=OE=OF=r, 连接OA、OB、OC, 则SΔABC=SΔOAB+SΔOBC+SΔOAC =1/2ra+1/2rb+1/2rc =1/2r(a+b+c).

蔚汤鸣4143如图,AD是△ABC的角平分线,DE⊥AC于E点,DF⊥AB于F点.若AB+AC=18,S△ABC=36,求DF的长. -
洪忽弦13848765365 ______[答案] ∵AD是△ABC的角平分线,DE⊥AC于E点,DF⊥AB于F点, ∴DF=DE, ∵S△ABD+S△ADC=S△ABC, ∴ 1 2*AB*DF+ 1 2*AC*DE=36,又AB+AC=18, ∴DF=DE=4.