【单选题】The types of short-circuit in three-phase system are three-phase short-circuit, two-phase short-circuit, two-phase short-circuit grounding and single-phase short-circuit grounding. When the three phases of the system are short-circuited, they are still in the symmetrical stated. Other types of shorted circuit are asymmetric short circuit. Which of the following types is a symmetrical short circuit? A. Single phsae ground short circuit B. Three phase short circuit C. Two phase short circuit D. Two phase ground short circuit

For a neutral-unearthing system, during a bolted single line-to-ground fault, the non-fault phase voltage and the fault phase voltage are ()respectively. A: phase voltage and zero B: phase voltage and line-to-line voltage C: line-to-line voltage and phase voltage D: line-to-line voltage and zero

During<br/>cooling of a material, when a single phase solid transforms directly<br/>to two-phase solid, this is called a ( ) reaction. A: isomorphous B: eutectic C: peritectic D: eutectoid

At a ( ) fault of the<br/>system, the non-fault phase voltage will increase with the<br/>zero-sequence impedance. A: three-phase fault B: double line-to-ground fault C: line-to-line fault D: single line-to-ground fault

Which of the following is not a CT phase of COVID-19? A: Early phase B: General phase C: Progressive phase D: Critical phase E: Resolutive phase

（Single choice）（2 points）Regarding the budget preparation, what is done during the feasibility study phase is ( ) A: Construction drawing budget B: Project settlement C: Investment estimate D: Design estimates

100%<br/>Protection for generator stator single phase earth fault() A: zero<br/>sequence voltage protection B: third<br/>harmonic voltage protection C: zreo<br/>sequence current

The first phase of the stress response, or General Adaptation<br/>Syndrome is called the ( ). A: Resistance phase B: Adaptation phase C: Alarm phase D: Fight-or-flight phase

The three-phase composition of soil refers to solid phase, liquid phase and gas phase

‍The poor implementation of the performance planning phase will result in the poor implementation of the:‏‍‏ A: performance execution phase B: performance assessment phase C: performance review phase D: performance renewal and recontracting phase