A.a cheap pen could be designed with great commercial success
B.a firm was not established to produce high-quality ballpoint pens
C.most people could not afford such a firmly established invention
D.the ballpoint pens available were expensive despite their poor quality

A.From Mobile Devices to Ballpoint Pens
B.From a Luxury Item to an Everyday Object
C.Ballpoint Pen's New Design - For Better or Worse?
D.Biros - A Business Model in Britain

A.From Mobile Devices to Ballpoint Pens
B.From a Luxury Item to an Everyday Object
C.Ballpoint Pen's New Design - For Better or Worse?
D.Biros - A Business Model in Britain

A.arises
B.boosts
C.mounts
D.surges

A.every
B.another
C.much
D.many

A.whom
B.which
C.where
D.when

A.popular
B.popularly
C.popularise
D.popularity

A.\(8\)
B.\(9\)
C.\(1\)
D.Vô số

A.11
B.14
C.5
D.13

A.\(y = \dfrac{{x + 1}}{{x-2}}.\)
B.\(y = {x^2} + 2x\).
C.\(y = {x^3}-{x^2} + x\)
D.\(y = {x^4}-3{x^2} + 2\).