a: 0,6m=60cm

a/b=60/70=6/7

b: 0,2 tạ=20kg

a/b=20/12=5/3

c: 75cm=3/4

a/b=2/3:3/4=2/3*4/3=8/9

d: 3/10h=18p

=>a/b=18/20=9/10

1 D

2 D

3 A

4 D

5 C

II

6 A

7 B

8 A

9 B

10 D

11 B

\(a,\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{4}{7}+\dfrac{1}{7}+\dfrac{2}{7}\right)=1+1=2\)

\(b,\left(\dfrac{1}{3}+\dfrac{4}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{6}+\dfrac{2}{6}+\dfrac{5}{6}\right)=\dfrac{7}{3}+\dfrac{4}{3}=\dfrac{11}{3}\)

a)\(\dfrac{3}{5}+\dfrac{4}{7}+\dfrac{2}{5}+\dfrac{1}{7}+\dfrac{2}{7}\)

\(=\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{4}{7}+\dfrac{1}{7}+\dfrac{2}{7}\right)\)

\(=1+1\)

\(=2\)

b)\(\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{4}{3}+\dfrac{2}{6}+\dfrac{2}{3}+\dfrac{5}{6}\)

\(=\left(\dfrac{1}{3}+\dfrac{4}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{6}+\dfrac{2}{6}+\dfrac{5}{6}\right)\)

\(=\dfrac{7}{3}+\dfrac{4}{3}\)

\(=\dfrac{11}{3}\)

1,..7) SGK

8, 

\(i=90^o-60^o=30^o\)

\(i=i'\Leftrightarrow i'=30^o\)

☛ Đáp án:   B. Môi trường ôn đới lục địa

uses crt;

var r,cv,dt: real;

const pi=3.14;

begin

clrscr;

write('Nhap ban kinh r: '); readln(r);

cv:=2*pi*r;

writeln('Chu vi= ',cv:0:2);

dt:=pi*r*r;

writeln('Dien tich= ',dt:0:2);

readln;

end.