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Choose B1, hundreds of students means hundreds of students, is an approximation, this question is about the same as about, so do not choose A

2. Two hundred students use tow hundred student, no need to add of, so don't choose C.

3. When adding quantifiers in front of hundred, do not use the plural form, such as one hundred, five hundred, and there is no tow hundreds, so do not choose d

ca hundreds of means hundreds of people means approximate number, hundreds.

b two hundred table exact number, 200c two hundred of after plus range and so on.

d Not having such a collocation is itself wrong.

Last Thursday, about () students from our grade went to the Museum of Science and Technology.

Approximately (how many) of our grade level came to the Science and Technology Museum last Thursday?

Choose a after the translation. Hundreds of grade students want to go to the Museum of Science or Industrial Technology next Thursday. Usage of hundred.

If there is a number in front of it, you can't add s or ofWhen you don't count the words, you must add s and bring ofThere are two ways to write it.

1.The number hundred of then your Thursday is one less s, which should be thursday

Find the distribution law first, and then the mathematical expectation.

Draw 3 balls.

The maximum number of the ball.

p(ξ=2) =1/5c3 =1/10

p(ξ=3) =3/5c3 =3/10

p(ξ=4) =6/5c3 =6/10e(ξ)ans :b

A is a cycle from 1 to 4.

According to this rule, the segment stove 2004 4=501 is just an integer number of volt-fuel dismantling cycles.

Therefore, 2004 should be in the equivalent of 4.

So. The direction of the arrows from 2004 to 2005 to 2006 is indicated by the arrows of a.

There is a very chaotic and obvious periodicity.

Apparently there is no first file 4 in a cycle, right?

So the situation of 2004->2005->2006 should be the same as the situation of Chaxiao 0->1->2 So a

（1）a(n+1)^2-an^2=s(n+1)+sn-sn-s(n-1)=a(n+1)-an

a(n+1)+an][a(n+1)-an]=a(n+1)-an

a(n+1)=an or a(n+1)=-an+1 (because an's constant "0", so discard).

So an=a2

And because a2 2=s2+s1=a2+2a1=a2+2

a2-2)(a2+1)=0

a2 = 2 or -1 (rounded).

So the general formula is: when n=1, an=1;When n>=2, an=2

log(2,b1*b2*..bn)=log=n(n+1)/2

log(2,b1)+log(2,b2)+.log(2,bn)=n(n+1)/2

log(2,bn)=n(n+1)/2-(n-1)n/2=n

bn=2^n

2) When n=1, an*bn=2;When n>=2, an*bn=2 (n+1).

So when n=1, tn=a1*b1=2

When n>=2, tn=a1*b1+a2*b2+.an*bn

2+2^3+2^4+..2^(n+1)

2[1-2^(n+1)]/(1-2)-4

2^(n+2)-6

There are 61 days in total, 61 7 = 8 ......5, Friday.

I choose A, 4 pcs.

Take the middle point D of the hypotenuse AB and connect the CD to obtain 2 isosceles triangles;

According to the figure, set the right-angled edge ACBC

You can find a point E on the hypotenuse, satisfy CE=CB, and form a waist triangle of equal socks;

Find a point f on the long right-angled side ac, satisfy af=bf, and form a triangle with equal finches.