Their income is ________________(一般家庭的3～5倍).

　　答案：three to five times that of ordinary households

　　解析：本題考查數(shù)的表達(dá)。考生要學(xué)會(huì)用"倍數(shù)+the size (length,volume) of..."，"...倍數(shù)+that of (what it was)..."的句型進(jìn)行倍數(shù)的表達(dá)。Household是個(gè)集合詞，表示家庭，如：average household(中等家庭);multiperson household(多人口家庭);peasant household(農(nóng)戶)。"家務(wù)"叫做household affairs。