A. causes B. cause C. caused D. causing
A. is; are B. are; is C. are; are D. is; is
A. is; are B. are; is C. has; have been D. have; has been
A. have tried B. have been tried C. has been tried D. has tried
A. has B. have C. is D. are
A. were; have B. were; has C. was; has D. was; have
A. is knowing B. knows C. have known D. has known
A. is more expensive B. is much higher C. are much higher D. are much lower
A. is made B. are made C. has made D. have made
A. is; well B. has; can C. are; must D. have;should