28. 掌握以下常见标志： ENTRANCE EXIT PUSH PULL NO SMOKING NO PARKING FRAGILE THIS SIDE UP NO PHOTOS DANGER BUSINESS HOURS PLAY STOP PAUSE ON OFF

IV. 重要语法

27. --- The hole should not be too deep.

26. --- The (ground ) must be just right…

25. --- More or less!

24. --- The more, the better.

23. --- The Great Green Wall is 7000 kilometres long, and between 400 and 1700 kilometres wide.

22. --- The hole should not be too deep.

21. --- It's best to …

20. --- The (ground ) must be just right…

19. --- Where is / are … grown / produced / made ?