1.He was too cautious to venture upon such a dangerous expedition.
由于过分谨慎,他不敢从事那么危险的探险。
2.They returned safe and sound from a dangerous expedition.
他们冒死探险,现已平安归来。*
3.They started on a dangerous expedition.
他们出发去进行一次危险的远征。
4.to return safe and sound from a dangerous expedition
从危险的远征中平安无恙地归来