[观察例句]
①The building being built is a new shopping mall.
②Jim has retired，but he still remembers the happy time spent with his students.
③A 13year study of early childhood development made by Harvard University has shown that，by the age of three，most children have the big potential to understand about 1，000 words.
④Painted by Leonardo da Vinci in the year 1503—1506，the Mona Lisa is a mysterious masterpiece.
⑤Many airlines now allow passengers to print their boarding passes online to save their valuable time.
⑥The national park has a large collection of wildlife，ranging from butterflies to elephants.
⑦It's wrong to leave the computer working.
⑧The old man found his hometown much changed.
⑨We hurriedly ended the meeting，leaving many problems to be settled.
