`9.` I suggest using gas instead of burning coal. ( suggest+ V-ing: đề nghị làm điều gì )
`10,` Because he was lazy, he failed the exam. ( sau because phải là một mệnh đề )
`11.` I am looking forward to seeing her at Christmas. ( looking forward to+ V-ing: mong chờ, mong đợi)
`12.` Does it take you three hours to surf the web every evening ? ( S+ spend+ time/money+ V-ing = It takes+ S+ time+ to V-inf )
`13.` I suggest waiting for the next train. ( suggest+ V-ing: đề nghị )
