Phrases with the structure 时A时B
Phrases with the structure 时A时B 
are set expressions that need to be memorized.
In the structure, "A" and "B" are replaced by monosyllabic adjectives with opposite meanings.
are set expressions that need to be memorized.
In the structure, "A" and "B" are replaced by monosyllabic adjectives with opposite meanings.Here are some examples of these set expressions:
时好时坏
时长时段
时宽时窄
时长时段
时宽时窄 Pay attention
If a phrase with the structure 时A时B is placed before a noun, the particle 的 is usually placed between the noun and the structure.
is usually placed between the noun and the structure.Examples
时宽时窄的山路
The mountain roads are sometimes wide and sometimes narrow
他的成绩时好时坏，父母也不知道怎么办
His parents don't know what to do. His grades are sometimes good and sometimes bad
tā de chéngjī shí hǎo shí huài, fùmǔ yě bù zhīdào zěnme bàn