1. Population tends to concentrate in large cities. (Àα¸´Â ´ëµµ½Ã¿¡ ÁýÁßÇÏ´Â °æÇâÀÌ ÀÖ´Ù) 2. concentrate rays to a focus (±¤¼±À» ÃÊÁ¡¿¡ ÁýÁßÇÏ´Ù) 3. concentrate one's energies on (¡¦¿¡ ¸ðµç Á¤·ÂÀ» ÁýÁßÇÏ´Ù) 4. He is unable to concentrate his thoughts upon his academic work. (±×´Â Çо÷¿¡ Àü³äÇÒ ¼ö°¡ ¾ø´Ù) 5. concentrate upon a problem (¾î¶² ¹®Á¦¿¡ Àü³äÇÏ´Ù)