_____ all the inventions have in common is ______ they have succeeded

A.all insects will be eliminated

B.all insecticides will be abandoned

C.super-bugs resistant to all poisons come out

D.scientists must invent new insecticides

A.it led to many other inventions

B.man had no use for it then

C.there were no wheels in nature

D.all of the above

A.it led to many other inventions

B.man had no use for it then

C.there were no wheels in nature

D.all of the above

A.<>A.it led to many other inventions

B.man had no use for it then

C.there were no wheels in nature

D.all of the above

A.he could use a steel needle-like tool instead of a key

B.he could invent all kinds of knots and locks in a minute

C.he could free himself quickly while bound or locked up

D.he made a close study of all types of lock

Scientists want to postpone the day when______.

A．all insects will be eliminated

B．all insecticides will be abandoned

C．super-bugs resistant to all poisons come out

D．scientists must invent new insecticides

A.he could use a steel needle-like tool instead of a key

B.he could invent all kinds of knots and locks in a minute

C.he could free himself quickly while bound or locked up

D.he made a close study of all types of lock

Which of the following statements is NOT true of scientists in earlier times？

A．They invented false theories to explain things they didn't understand.

B．They falsely claimed to know all about nature.

C．They did not believe in results from scientific observation.

D．They paid little attention to the problems they didn't understand.

Harry Houdini's best art was perhaps that______.

A．he could use a steel needle-like tool instead of a key

B．he could invent all kinds of knots and locks in a minute

C．he could free himself quickly while bound or locked up

D．he made a close study of all types of lock

Which of the following statements is NOT true of scientists in earlier times？

A．They invented false theories to explain things they didn't understand.

B．They falsely claimed to know all about nature.

C．They did not believe in results from scientific observation.

D．They paid little attention to the problems they didn't understand.