_____ economically, one tin of oil will last at least three months.
A. To use
B. To be used
C. Using
D. Used
Human ________ is controlled by reason as well as instincts.
A. behavior
B. behave
C. belief
D. behaving
Human beings are different from animals _____ they can make use of languages.
A. whereas
B. in that
C. because of
D. consequently
号灯应在下列时间内显示____。
A. 从日没到日出
B. 在任何情况下
C. A+B
D. A、B均不正确