青云翻译

There are four main methods of study were observational studies, theoretical studies, numerical model studies and experimental studies

There are four main research methods, namely research, theoretical study for the observations, numerical model and experimental research

The research method mainly has four kinds, respectively be observation research, fundamental research, value pattern research and experimental study

There are four main types of research methods, respectively, and theoretical research, and observation, study numerical models research and experimental research

There are four main research methods, namely research, theoretical study for the observations, numerical model and experimental research