Apply the course version boundaries in notes.md; HSK tasks are transferable language practice, not a claimed HSK 3.0 mock.
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gre_psychology:mixed-revision:1
A researcher assigns volunteers randomly to two study methods. Identify what random assignment addresses and what volunteer recruitment still limits.
Answer and reasoning · Respuesta y razonamiento
Random assignment reduces systematic confounding between groups. Volunteer recruitment may limit generalisability; assignment is not random sampling.
gre_psychology:mixed-revision:2
A bell repeatedly precedes food and later evokes salivation. Identify the learned cue and distinguish reinforcement of a voluntary action.
Answer and reasoning · Respuesta y razonamiento
The bell becomes a conditioned stimulus in classical conditioning. Operant reinforcement depends on consequences of an action, rather than a predictive cue-food pairing alone.
gre_psychology:mixed-revision:3
A test is stable across administrations but systematically underestimates the target skill. Explain reliability and validity separately.
Answer and reasoning · Respuesta y razonamiento
Stable measurements support test-retest reliability. Systematic underestimation challenges the proposed interpretation; reliability does not establish validity.