234. After the 1911 Revolution, China began to use the Gregorian calendar (solar calendar) and at the same we have also used the lunar calendar(阴历) in which a leap year (闰年)______ every four years.
____ the expense, I ____ a round-the-world tour.
____ you dislike ancient buildings, Warrick Castle is worth a visit.
It was dark and cold. They had to find a house ____ and some wood ____.
The house built of stone lasts longer than ____ built of wood.
It is ______ that terrorism is a great threat to world peace.