摸不著頭腦

feel with the hand; to touch; to stroke; to grope; to feel (one's pulse); imitate; copy

particle indicating the successful result of a verb; to touch; to come in contact with; to feel; to be affected by; to catch fire; to fall asleep; to burn; particle attached after verb to indicate action in progress, like ‑ing ending; to make known; to show; to prove; to write; book; outstanding; to wear (clothes); to contact; to use; to apply; catch; receive; suffer

head and brain; head; mind; brains; head