geochemical characteristics characteristics

Ability of coping with difficulty

Acculturation difficulty

analysis difficulty

Assessment of the difficulty or simplify

breeding difficulty

caving difficulty degree

classification of difficulty degree

closure difficulty

Construction Difficulty

degree of difficulty

degree of difficulty of separation

Difficulty

difficulty analysis

difficulty and challenge

difficulty and contradiction

difficulty and countermeasure

difficulty and hot spot of pharmacokinetics study

difficulty and pain in micturition

difficulty and problem