This study proposes how to teach aspectual derivations of the verb in the Russian language based on the prefixation and suffixation. The author argues that for the intermediate/advanced learners the traditional aspectual pair system needs to be replaced by the aspectual cluster system and the derivations of the imperfective verbs through the suffixation needs to be taught based on the classification of the infinitives. The hierarchical structure of verb stem in Russian is as follows: superlexical prefixes (po-, etc.) > -yva- > superlexical prefixes (ot-, etc.) > intermediate prefixes (do-, pere-) > -nu-/-a- > lexical prefixes > stem. The study also proposes that the syntactic structure needs to contain the split AspPs (PerfP1 > ImpfP > PerfP2 > PerfP3) outside of the vP and another AspP inside the vP in order to derive the above-mentioned hierarchical structure.

Using the known result of the expected busy period for a controllable M/G/1 queueing model operating under the triadic Max (N, T, D) policy, its upper and lower bounds are derived to approximate its corresponding actual value. Both bounds are represented

Us ing the known result of the expected bllsy period for the triadic Min (N, T, 0) operating po licy applied to a controllable M/GI1 queueing model, its upper and lower bounds are derived to approximate its corresponding ac tual value. 80th bounds are rep

Using the results of the expected busy periods for the dyadic Min(N, D) and Max(N, D) operating policies in a controllable M/G/1 queueing model, an important relation between them is derived. The derived relation represents the complementary property betw