Geometry is the branch of mathematics ________ the properties of lines, curves, shapes, and surfaces. a. that concerned with b. it is concerned with c. concerned with d. its concerns are _________ for a career in dance generally begins at an early age. a. People train b. That people train c. If training d. Training 여기서 답은 d 인데 주어 역할을 하는 that 절 b는 안되나요? An electromagnet is created _________ electrical current through a coil of wire. a. by passing b. passes by c. to be passed d. passed 여기서 a 인데 다른것은 왜안되는지.