x(1-x) y'' + [c - (a+b+1)x] y' - aby = 0

must be made by 18 march
必须在3月18了
双语对照
例句:
1.
Payment must be made by bank draft.
必须以银行汇票的方式付款.
如有不懂,

远不远?
远的,所以我乘火车去.

选A.sometimes是指有时候；sometime指某时；some times是指几次；some time是指一段时间.

很高兴能够在这里回答你的问题,
They are going to camp by the lake.
他们准备去湖边野营.
by the lake 湖边

直译：我的人生----被你们中的一个——从我自己那里夺走了.
意译：你们中的一个夺走了我的人生（或生命）.
没有上下文,将就翻译了一下.

D

drives to

e used for意为“（某物）被用做……”其后接名词、代词或动名词.如：
A knife can be used for cutting bread .刀可用来切面包.
be used by的意思是“由（被）……使用.”
be used to doing 习惯于… used to do sth.过去常常…
be used to do sth.也可表示“（某物）被用做……”,但其后接动词原形.

ax+bx+cx=(a+b+c)x,ay+by+cy=(a+b+c)y,az+bz+cz=(a+b+c)z,xm+ym+zm=(x+y+z)m,
(a+b+c)x+(a+b+c)y+(a+b+c)z
(a+b+c)(x+y+z)=(x+y+z)m
m=a+b+c

(ax+by)^2+4(mx-ny)(ax+by)+4(mx-ny)^2 = [ (ax + by) + 2(mx - ny) ] ²
所以原式=[ (ax + by) + 2(mx - ny) ] ² +2[ (a + 2m)x + (b - 2n)y ] + 1
.=[ (a + 2m)x + (b - 2n)y ] ² + 2[ (a + 2m)x + (b - 2n)y ] + 1
.=[ (a + 2m)x + (b - 2n)y + 1 ] ²

首先 这个句子中有两次地方提醒了你要用到完成时
1.by the end of 在……之前 2.for ten years 十年了 表示时间段
所以在这里我们应该用到完成时 现在完成时 所以是have known
我们不需要用现在完成进行时 我们为什么要去强调我们以后还会认识呢
而且在这里时间也不是 过去的过去 所以不用 过去完成时

ax+by-ay-bx
=x(a-b)-y(a-b)
=(a-b)(x-y)

原式=a²x²+2abxy+b²y²+a²y²-2abxy+b²x²
=(a²x²+a²y²)+(b²x²+b²y²)
=a²(x²+y²)+b²(x²+y²)
=(x²+y²)(a²+b²)

B

如果从句中缺少状语,则用介词+which 其实就相当于where和when的效果 .
which前的介词跟定语从句修饰的内容有关,被修饰的内容与什么介词搭配,which前就用什么介词,如He choose the way in which he can finish his work better.因为way和in才能搭配,故which前用in ; ...看先行词需要什么介词搭配,例如先行词是school,那就是缺at,因为是at school

你这么做是什么意思?

A

应该是这样
up 9.5% on last year 去年基础上上升9.5%
up by 20% year-on-year 去年同期比,上升了20%

Casablance
卡萨布兰卡
Bertie Higgins / 帕帝•希金斯
I fell in love with you
Watching Casablanca
Back row at the driving show
In the flickering light
Pop-corn and cokes
Beneath the stars
Became champagne caviar
Making love
On a long hot summer’s night
I thought you felt in love with me
Watching Casablanca
Holding hands beneath the paddle fans
In Rick’s candle-lit café
Hiding in the shadows from the spots
Moroccan moonlight in your eyes
Making magic at the movies
In my old Chevrolet
Oh a kiss is still a kiss
In Casablanca
A kiss is not a kiss without your sigh
Please come back to me
In Casablanca
I love you more and more each day
As time goes by
I guess there are many broken hearts
In Casablanca
You know I’ve never really been there
So I don’t know
I guess our love story will never be seen
On the big wide silver screen
But it hurt just as bad
When I had to watch you go
Oh a kiss is still a kiss
In Casablanca
A kiss is not a kiss without your sigh
Please come back to me
In Casablanca
I love you more and more each day
As time goes by

(ax+by)²-(ay+bx)²
=(ax+by+ay+bx)(ax+by-ay-bx)
=[a(x+y)+b(x+y)][a(x-y)-b(x-y)]
=(a+b)(x+y)(x-y)(a-b)

B：当然,是对疑问的回答 D：好主意,是对建议的回答
而问题Are we going there by bus?是由陈述句 we are doing there by bus 转换而来的一般疑问句,翻译成“我们坐公交车去吗”,表示询问,并不表示建议.

We can tell the time by __a____ __watch_____ or by a clock.
A watch has two or three __hands____ on its __face_____.
A __clock____ is bigger than a watch.
People often put the clock __on____ _the______ ___top___ ___of____ ___wall___ .
Tom's ___clock___ can speak and call him to __wake____ ___up___ every day.

making用ing形式

Jim was w(alking)by and just heard Tom is talk with Mary

也许是..提问者在问一位夫人以及这个夫人的同伴,那位妇人说“我们”是说她和她的同伴们,她们在照相所以没看到提问者所说的红帽子男人

他们乘车去动物园,by 是通过某种方式