• 天(sky; vast)
• 口(mouth; opening)

A gaping mouth as wide as the sky stuffed inside represents swallowing whole.

• 口(mouth; opening)
• 因(cause; origin; support; basis)

The throat is where the mouth relies on to swallow food down into the belly.

• 囗(surround; fence)
• 木(tree; wood)

A tree surrounded and trapped on all four sides with no way to escape represents hardship.

• 又(hand; again)
• 隹(short-tailed bird)

Catching a short-tailed bird in flight with bare hands is as difficult as the challenge this character represents.

• 天(sky; vast)
• 口(mouth; opening)

A gaping mouth as wide as the sky stuffed inside represents swallowing whole.

• 口(mouth; opening)
• 因(cause; origin; support; basis)

The throat is where the mouth relies on to swallow food down into the belly.

• 囗(surround; fence)
• 木(tree; wood)

A tree surrounded and trapped on all four sides with no way to escape represents hardship.

• 又(hand; again)
• 隹(short-tailed bird)

Catching a short-tailed bird in flight with bare hands is as difficult as the challenge this character represents.