The speed of cars and trucks is ________ 30 kilometers per hour in large cities in China.
| A．limited | B．limiting | C．limiting to | D．limited to |
. When he was working there he caught a serious illness from _____ efforts he still suffers.
| A．which | B．that | C．whose | D．what |
. Luckily, we’d brought a road map without ______ we would have lost our way.
| A．it | B．that | C．this | D．which |
Is this the reason _______ at the meeting for his carelessness in his work？
| A．he explained | B．what he explained | C．how he explained | D．why he explained |
All of the flowers now raised here have developed from those _______ in the forest.
| A．once they grew | B．they grew once | C．they once grew | D．once grew |
Our company will move to a tall building _______ we worked two years ago.
| A．where | B．when | C．that | D．which |