![](https://static.youtibao.com/asksite/comm/h5/images/m_q_title.png)
Be careful! The knife is very _____.
A.old
B.sharp
C.fast
D.light
![](https://static.youtibao.com/asksite/comm/h5/images/solist_ts.png)
A.old
B.sharp
C.fast
D.light
A.effective
B. sensitive
C. ordinary
D. careful
You cannot be______ careful when driving a car on the superhighway.
A.very
B.too
C.so
D.enough
A.encounter
B.challenge
C.face with
D.experience
A. took care of
B. took a care of
C. careful
D. care much
Halley made his discovery ______.
A.by doing experiments
B.by means of his own careful observation
C.by using the work of other scientists
D.by chance
This article means to say that a careful driver travels about ______.
A.75 miles per hour
B.65 miles per hour
C.55 miles per hour
D.10 miles per hour
The author assumes that his readers are__________ the basic concepts.
A. careful with
B. careful to
C. familiar with
D. familiar to
A.save up
B.cut through
C.leave out
D.take out