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We constrain models of single field inflation with the pre-\textit{Planck}CMB data. The data used here is the 9-year Wilkinson Microwave Anisotropy Probe(\textit{WMAP}) data, South Pole Telescope (SPT) data and Atacama CosmologyTelescope (ACT) data. By adding in running of spectral index parameter, we findthat the $\chi^2$ is improved by a factor of $\Delta \chi^2=8.44$, whichstrongly indicates the preference of this parameter from current data. Inaddition, we find that the running of spectral index $\alpha_s$ does not changevery much even if we switch to different pivot scales, which suggests that thepower law expansion of power spectrum is accurate enough till the 1st orderterm. Furthermore, we find that the joint constraints on $r-n_{s}$ give verytight constraints on single-field inflation models, and the models with powerlaw potential $\phi^{p}$ can only survive if $0.9 \lesssim p \lesssim 2.1$, soa large class of inflation models have already been ruled out before\textit{Planck} data. Finally, we use the $f_{NL}$ data to constrain thenon-trivial sound speed $c_s$. We find that the current constraint is dominatedby the power spectrum constraints which have some inconsistency with theconstraints from $f_{NL}$. This poses important questions of consistencybetween power spectrum and bispectrum of \textit{WMAP} data.

Constraints on single-field inflation with WMAP, SPT and ACT data -- A last-minute stand before Planck