1.2 Objectives of this Book

The objective of this study is three-fold.First，it attempts to describe TSSs from both formal and functional perspectives.In particular，it attempts to address the role of TSSs in conveying attitudes toward propositions，maintaining writer-reader interactions and keeping the balance between showing confidence and exercising caution in claim-making.

Second，it aims to explore the cross-linguistic equivalence between TSSs and corresponding Chinese expressions in academic texts，with a view to identifying Chinese equivalents of TSSs，patterns and lexical sequences，and distinguishing between different types of equivalence and translation units.

Third，this study attempts to examine co-selections involved in the use of TSSs by investigating relations between lexis，grammar，meaning，function and other contextual factors.A parallel aim is to uncover similarities and differences in co-selection between functionally equivalent expressions.