通常电视发射天线采用的是（）方式。A.垂直极化B.水平极化C.圆极化D.

As to the issue of drug approval, ______.

A．to judge whether a drug is safe enough should rely on objective measures

B．drug companies usually study for years to prove the safety and effectiveness of a drug

C．drug companies prefer surrogate endpoints in the process of drug approval because F.D.A.encourages them to do so

D．drug companies rely heavily on surrogated endpoints because this way of measurement takes less time and money

A、Adding substances or energy that harm the environment.

B、Changing the population growth of species.

C、The decrease in the quality of the environment as a result of natural events

D、Substances or materials that are toxic to humans decreasing the quality of the human environment.

A．the quality of a brand is measured by the service quality of the store selling it

B．the quality of a product determines the quality of its distributors

C．the popularity of a brand is determined by the stores that sell it

D．consumers believe that first-rate products are only sold by high -quality stores

A．the quality of a brand is measured by the service quality of the store selling it

B．the quality of a product determines the quality of its distributors

C．the popularity of a brand is determined by the stores that sell it

D．consumers believe that first-rate products are only sold by high-quality stores