埃博拉疫情在西非地区肆虐,世界卫生组织官员称感染总案例数可能超过两万人,医学界尚未找到预防该病毒的疫苗和其来源,也没有发现有效的治疗方法。从哲学角度看这是因为
When our parents are not at home, we need to ______ ourselves.
The volunteers kept on searching for the missing people in the earthquake, _____they were hungry and tired.
--- Shall we take a bus to the library? --- It’s not far. I think we________ take a bus. Let’s walk there.
—When did you start to collect stamps? —I got my ______ stamp when I was ______ years old.
_____ Henry’s mother _____ his father speaks English. They both speak Chinese.