Tìm nghiệm nguyên dương

xyz(\(\dfrac{1}{x^2}+\dfrac{1}{y^2}+\dfrac{1}{z^2}\)) = 3

Supply the correct tense or form of the verbs in the brackets

1. The secretary (write) the report for nearly 2 hours and she (write) 4 pages.

2. why (you/always/talk)? I suggest you (concentrate) on your work.

3. I (clean) the bookshelf when I (come) across this old photo.

4. (Write) the letter, she (put) it carefully in an envelope