playround

1. drives / is going

2. Will... buy...

\(\frac{5}{3}+\frac{5}{15}+\frac{5}{35}+\frac{5}{63}+\frac{5}{99}+\frac{5}{143}\)

\(=\frac{5}{2}\cdot\left(\frac{2}{1\cdot3}+\frac{2}{3\cdot5}+...+\frac{2}{11\cdot13}\right)\)

\(=\frac{5}{2}\cdot\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{11}-\frac{1}{13}\right)\)

\(=\frac{5}{2}\cdot\left(1-\frac{1}{13}\right)\)

\(=\frac{5}{2}\cdot\frac{12}{13}\)

\(=\frac{30}{13}\)

1. Yesterday tom went to school by bike.

2. Yesterday she was going to the dentist.

3. Last year, Mr lan taught Math in high school.

4. Last month, did you fly to China?

eat có nghĩa là ăn

1. is reading

2. isn't listening

3. is coming

No

1. lives

2. works

3. don't fly

4. teaches