An abstract should be brief while containing as much information as it could, typically, it should be less than 300 words. Here are some points,

1） Use simple English

An abstract should reach as many readers/researchers as possible. Please do not use advanced grammar or words.

2) Tense

Use proper tense for abstract writing, simple present tense and simple past tense are mostly used.

3）Active voice/passive voice.

Both active and passive voices are used in abstract, however, active voiceis used more widely.  “A exceeds B” is a more preferable expression than “B is exceeded by A”。

4） Avoid unnecessary information 

eg: use at 250~300 ℃instead of at a temperature of 250 ℃ to 300 ℃  

use at 1.2 MPa instead of at a high pressure of 1.2 MPa

Avoid the words that have little connection with the content such as, “A method is described”，
“In this work”，
“It is reported that”,
“This paper is concerned with” ，
“Extensive investigations show that”。

“specially designed or formulated”，

“ The author discusses”，

“The author studied”

5）Say it scientifically
Use scientific words/expressions instead of colloquial words.

eg: use A should the property of high production of B instead of A produce large quantity of B