As a matter of fact, the factors affect the ratio through influencing the boy preference and the attainability of the B-ultrasonic. 事实上，这些因素通过影响男孩偏好和B超的可获得性而影响出生性别比。
attainability
“ -ability” ⌜ 具备某种特定能力 - the quality of being able to do something ~ ⌟
