手机网络技术的发展为文化交流带来了强有力的现代科学技术的支撑,也为不良文化的传播提供了现代化的途径。这说明
You should ___ the lights if there is no one in the room.
Save water as ___ as we can.
--What’s the time ___ your watch?---On, my watch ___ “A quarter to five”
--____ did he send this letter to you? ---By mail
--Let’s go to see our teacher. ---_____.