单项选择题

The use of helium for deep-sea diving

A．helped to overcome the physical discomforts the divers experienced when nitrogen was used.
B．was found by Dr. Jeol Hiderbrand.
C．is still universally acknowledged as standard practice up to now.
D．all that is included in A, B, and C.

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单项选择题

Evidence indicated that a high percentage of fathers were involved in the parenting process which amounted to

A．about two-thirds of the fathers involved in the study.
B．slightly less than half of the fathers studied.
C．more than three-quarters of all the fathers.
D．a little less than one hundred percent of all fathers.

单项选择题

The data accumulated was obtained through

A．observation by social psychologists.
B．conversations with mothers of the children.
C．interviews, school records and physician' reports.
D．observations of fathers with their children.